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Wiki suggests 32W per tealight.
Google suggests £5 for 100 is the going rate.
So 3.2KW of energy for £5.
Doesn’t seem that cheap even before you burn your house down…
So having had a few rads refusing to heat up downstairs we got a guy in to do a powerflush today.
While the pump was running got all of the rads nice and hot, flushed out loads of crap and refilled with clean water expecting it to sort the problem.
Back on to the normal pump and the same rads are still not getting off cold.
The powerflush didn't bypass any valves so we can rule that out.
Shouldn't be any muck left in the system either.
Pipes either side of the pump are very hot and the pump is whirring away like a good 'un and was cleaned out during the flush and found to be in good working order.
Rads were working fine last Spring and didnt't notice anything over summer, but why would you. Heat in downstairs rads didn't stop overnight, they got gradually worse over a month or so when we started using heating more in Autumn.
All upstairs rads getting nice and hot and if we lock them all down it still isn't getting the downstairs ones any warmer.
Short of taking all of the floors up ( a little difficult with a wheelchair user in the house) does anyone have any thoughts on what else it could be.
Wheres the boiler?
Is it system or combi ( no hot water tank)?
Airlock somewhere when it was refilled.
Boiler downstairs in Kitchen, pump in airing cupboard upstairs, boiler is heat only. HW tank in loft.
HW all fine, rads upstairs all fine.
System all bled after refill and it's doing exactly the same thing as it was doing before.
If we have to lift the floors we have to find accessible accommodation for our daughter and her care team so any insights would be greatly appreciated.
Wiki suggests 32W per tealight.
I read 80.
@smokey_jo I think your pipes are fine if the powerflush worked. Have you tried increasing the pump flow/pressure? I would speak to a plumber if I were you and ask what your options are.
Pump is on max and according to the plumber able to pump a higher flow than a standard household pump. He said the powerflush was pushing around 4-5 times the flow though so would be more easily able to overcome anything partially blocking pipework.
It's looking like a floors up job
we have had similar in this cold spell, unfortunately the last rad on the loop is the living room one which is the one we'd like to get hot in preference, and it will eventually. But the others are calling for heat to get the TRV's up to temp first so the hot water keeps going through them and by the time it gets to the living room it's not hot enough to make a significant difference.
So I have to turn the bedroom ones down through the day to overcome that, and then reverse them and save the living room one in the morning. Except not now we're all off work and college and want the living room warm all day, not just evening.
Which leads neatly to the blog my ex-colleague writes, I linked previously about his (mainly successful) attempt to effectively go off grid using heat pumps, solar and battery storage but his blog yesterday was all about whether keeping the house warm overnight is economical vs letting it cool and then heating it more to get back to temp.
https://protonsforbreakfast.wordpress.com/2022/12/19/setback-should-you-lower-heating-overnight/
Ok, that helps somewhat.
So you have a system boiler in the kitchen, and a traditional, indirect hot water tank, heated by the boiler, upstairs in an airing cupboard.
This is strange though ax its the reverse of what you would expect, hot rads downstairs and colder upstairs.
This is the limit of my knowledge of S and Y heating layouts but hopefully Bear will be able to come up with an answer.
I think the pipework from the boiler heads straight to the upstairs airing cupboard which would explain hot rads upstairs. I think the downstairs rads are after the upstairs ones on the circuit.
If I lock all of the upstairs ones off it still doesn't the downstairs ones off cold though
Ok, by the power of googlefu i am now au fait with S and Y dhw systems.
I think your diverting valve might be issue here.
Although the pump is over specified for the task there is not enough flow or, and pressure to pump a decent rate round the system, but the power flush did.
So the hot ch fluid from the boiler is not making its way round the house sufficiently fast enough to heat the last, lower rads downstairs.
Habe you tried turnimg all the upstairs off at the locksheilds, not the trvs, amd, if you have one, shut off the hot water tamk inlet valve.
Then open fully the locksheilds and trvs downstairs
Be a fun 40 mins in your house this evening
Habe you tried turnimg all the upstairs off at the locksheilds, not the trvs, amd, if you have one, shut off the hot water tamk inlet valve.
Yup we tried that and nothing - not a sausage
It wasn't as fun as you make out it might have been though
I think the pipework from the boiler heads straight to the upstairs airing cupboard which would explain hot rads upstairs. I think the downstairs rads are after the upstairs ones on the circuit.
This is the case in our house, the downstairs rads get less warm even if the system is balanced due to a longer unlagged pipe run. But they still do get warm.
But the others are calling for heat to get the TRV’s up to temp first so the hot water keeps going through them and by the time it gets to the living room it’s not hot enough to make a significant difference.
The rads aren't in series.
Pump is knackered then.
If you manually shut off everything upstairs then no hot rads downstairs at all.
Did you check the return pipework temperature at the time?
Has it worked in the past?
What does the pump sound like? Bubbles or smooth hum?
Have you checked the bubble traps are working?
Was working fine in Autumn.
Pump has been inspected today and is fine.
Pump is smooth hum.
What does a bubble trap look like and how do I check it?
Return pipes are hot.
I have one lukewarm rad downstairs now after 3 hours of everything upstairs being locked off.
Trail_rat. Oh dear.
That’s a shame
I actually used to work in consumer protection in the 70’s. We would investigate such claims.
I asked a mate who recently retired about DFS constant sale (trading standards legislation on sale goods and claimed reductions specifies a set period during which the goods must have been sold at “full price”.) He said “yes, but legislation like that just doesn’t get administered any more. Budgets. A culture of deregulation.
So the buggers (all of em) can nowadays claim whatever they like.
Automatic bypass valve faulty is my guess.
Where would I find this auto bypass valve and how could I test whether it's faulty?
Daughter had something very similar, three way valve had broken up inside preventing rotation of the valve seat. New valve fixed it .
Bypass valves are in newer boilers.
On an older set up you left 1 rad with open valves, usually the bathroom towel rail. So in the event every trv had closed down the pump is not pumping against shut valves leading to high pressure and overheating.
They are usually located in the lower parts of tge boiler and bridge the inlet and outlet pipework.
With an adjustable set point so you keep spme pressure in the system.
https://www.toolstation.com/22mm-automatic-bypass-valve/p36612
Bypass valves are in newer boilers.
Older systems can have external ones, we have one. I tested it by screwing it in and out all the way, I could hear when it started closing or opening.
If you don't have at least 10% of the load on rads without a bypass then you need one; I do but I still have one anyway.
Thanks guys, I'll pass that on to the HEng and see if it motivates some thought and action 🙂
Still thinking 3 way diverting valve is doing something weird.
Maybe jamming without fully moving through its range of motion
Tired motor or debris on the seats at a guess
HEng says he didn't see a bypass valve on the system. It could be under the floorboards so will have to start pulling upstairs boards next.
If I can get away without pulling downstairs floor I'll count it as a win
There might not be one - it's unlikely to have been fitted in an inaccessible location, that would require deliberate bloodymindedness on the part of the installer.
It could be the 3 way valve. If you turn off the hot water, run a bath, then turn the heating on do you get hot water back?
Im leaning towards diverter valve sending flow round the cylinder permanently , or not fully switching between the 2 systems
Im flummoxed , but I just sell all the gubbins at work
I think you need to find the 22mm return pipe downstairs , are you on microbore? or PEx plastic barrier piped CH? or Trad copper with 22mm flow and returns then 15mm feeds to each rad off the loop?
If the downstairs 22mm pipes are too hot to hold on to there is no reason why the rads are still cold. Unless its something like an airlock or TRV fails to closed
So some overnight progress!
All upstairs Rads closed off and lockshields off got the first downstairs rad on the circuit hot.
Locked down that one and it got the next one hot.
By this time it was getting late so locked that one down and went to bed.
This morning the remaining 3 rads were all working, the final 2 not as hot as the 3rd last but still OK for room they are in.
As I've left for work I've opened the lockshields on the other downstairs rads and opened the other valves 1/2 turn off closed to see what happens.
All pipes to rads are 15mm copper, no idea what's under the floor but it could well be 15 again. Upstairs is 22mm in the airing cupboard as that was a new install around 10 years ago due to moving a bathroom.
Interesting. My last rad doesn't get as hot as the others due to being on the end of a long run, so that might not be avoidable.
Molgrips. Isn’t that a matter of “balancing”. Added a rad in a place we sold a while back and it was very much at the end of the run, basement of a 3 story house. It wasn’t heating at all, so the heating guy came back and tightened all the other lockshield valves a little, more on the rads nearer the boiler (called it “balancing”) - and that worked. In that case the lock shields throughout had been replaced and left fully open. Hence the lack of balance, as much of the heat was being lost through the earlier rads.
Trail_Rat. All. Update on my insulation efforts. It wasn’t possible to use the foam tubing on many of the pipes en route to the upstairs because they were only 10mm apart and from the wall. (Who designs clips fir heating pipes that are so tight to the wall!) . Those pipes leading upstairs were heating that utility room they passed through far too much. Wasteful.
So I pretty much had to use the silver coated. bubblewrap tape (I did consider spray foam but far too risky - a leak would have been a right mess). I overlapped the tape so it was predominantly a double layer. Tight around the pipes as per the instructions. .
The room definitely feels much much less heated now. Phew.
Now I’m thinking about heat loss to the well ventilated underfloor voids downstairs. I’ll have to swerve that though as it would be far too much disruption to lift all those boards.
So I pretty much had to use the silver coated. bubblewrap tape. I overlapped so it was predominantly a double layer.
You could have done felt then bubblewrap.
Molgrips. Isn’t that a matter of “balancing”
Yes, but that only works to a point and there are other inter-related factors at play in my system which is bargain basement. If you restrict flow on some rads they don't end up as hot so that room doesn't get as warm and may not get warm enough before the hallway does and turns the thermostat off. If you throttle the hallway down so it warms up more slowly then the boiler's flow temp might get too hot and start short cycling. I currently have most of the rads throttled right down except the kitchen which is fully open, and that rad still is 10C cooler than the boiler flow temp which isn't hot enough to heat the large and cold room. I could turn up the flow rate to the next setting (pump only has three discrete settings) but then the water is going through all the rads too fast and not cooling down enough so the return temps are higher resulting in lower efficiency. I could help this with larger rads in some of the rooms and a faster flow rate. But those rads would have TRVs so when they're closed there'd still be the same issue.
This is all because this boiler won't throttle down enough, and the pump only has three fixed settings. A new better boiler could give lower heat output when needed which would fix the short cycling problem, and an internal pump that can vary its own speed for optimum flow regardless of what rads are calling for heat.
But lagging the long run to the kitchen rad would help as I could keep the lower flow and still have the rad hot enough to warm the room. Of course, all the pipes should have been lagged, but hey ho.
Just done our monthly readings for Octopus, averaged 56h kW of gas per day over the last month, just over £7 a day to heat the rather leaky Victorian terrace. And that's with our rather miserly heating schedule.
Similar usage to last January, which I don't think was that cold, so we probably have reduced our usage a bit..
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Anyone done a proper test with reflective insulation behind the radiators?
I did one years ago, seemed to help slightly but I have now lost the rest of the roll, I think I threw it out.
Anyone done a proper test with reflective insulation behind the radiators?
I stuck some behind all the ones against solid walls many years ago as it was so cheap, didn't really matter if it worked or not...
So I've knocked up a bit of an app that hopefully gives me an idea of how much oil I'm burning.
A Raspberry Pi stuck inside the cover of my massive (old) boiler listens once a minute for it running via a £4 USB mini microphone.
When the sound level is above a certain level (i.e. the boiler is running) if fires off a webhook message to IFTTT which adds a row to a google spreadsheet - it fires another message when the sound drops below a certain level (i.e. the boiler has shut down).
This gives me the burn duration from which I get the oil used (a 1.35kg nozzle uses 1.65L of kero per hour).
On my phone I have an app that gets data from the spreadsheet, filters it and makes it look better - it also gives me a total volume used and the associated cost.
There will be some error as the pi might have run the script just before the boiler fires up, but it would hopefully get it on the following run 60 seconds later. Missing 1 minute of burn time is equivalent to 0.0275L of kero.... so I'm not too bothered, plus the pi could miss the boiler shutting off by 1 minute so it kinda evens out a bit!
It will be interesting to see how well it runs.
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We've just had a similar issue - my tale may give you some ideas...
Getting to the first cold weather in our new house showed our Central Heating (oil) was not really working as expected.
I'd already replaced the motor on the mid-position valve when we moved in as the heating was coming on with the hot water, but didn't bother changing the valve.
The Boiler thermostat was set at max and running constantly, but the radiators were not anything like as hot as the boiler outlet.
Worked out that two of three rads downstairs were not flowing. They were getting warm but the return was cold.
First I found all of the lockshields wide open including the hottest rads, no chance of being balanced!
Closed all of the rads down and even with the pump on high and all rads closed and backed off 1/4 of a turn couldn't get very good flow.
Assuming the rads/pipework must be blocked/airlocked, tried purging with a hosepipe on the bleed port - good flow both directions - no improvement.
Noticed that the feed to the Hot Water Coil was warm and decided that the diverter valve must have been passing to the Hot Water cylinder - so drained the system and swapped the valve entirely - still no change. Bugger.
Starting from absolute cold allowed me to realise that the downstairs Rad circuit was getting a hot return very quickly even with all rads still being cold on their returns. So somewhere I have a short circuit - but where...
Looking through previous estate agent photos on Zoopla, I spotted a radiator in the kitchen that has not been reinstated during renovation before we bought. The kitchen floor is Karndean on plywood, across half of the ground floor. Bugger.
Managed to find a bit of the circuit above ground boxed in behind the downstairs toilet, also found a 10mm flow and return heading off towards the position of the previously removed radiator. Bonus!
Started the boiler and as the heat started circulating, the 10mm pipes stayed cold - that's not it then. Bugger.
Ended up following the pipes under the floor - including lifting carpets and cutting new traps (although thankfully not under the karndean) to check for heat in the return line.
Eventually I narrowed it down to the flow and return branch to the Living room.
Ahhhh, I bet there is an old back boiler in the open fireplace that is still connected...
Dismantled the sofa and lifted the carpet in the living room, no sign of any pipes heading to the fireplace, just the single radiator - but hang on... Some wazzock has connected together the flow and return at the far end of the radiator.
Effectively there is a 15mm shunt across the bottom of the radiator - that would explain it!
Bear in mind I'm looking through a 12" single board width trap against the wall, a fix is tricky. Thankfully I managed to get my hand in with the pipeslice and then fit two push fit blanks - yes I have a dead leg, yes they are pushfit, but needs must!
Test fired the boiler again and found the problem had now shifted to the dining room. Same fix and try again...
SUCCESS!!!
Where success is measured as turning the boiler on and not getting a hot return for at least five minutes!
Turning the boiler stat down to a guestimated 60C, means a burner duty cycle of around 50% which should make a nice saving on oil usage. The rads are now actually heating the house!
Now all I need to do is get all the air out of the system and balance the radiators, then properly set up the boiler temp and flow rates.
Unfortunately we've used about 700L of oil for very little benefit before realising we had an issue...
Gas meter reader chap turned up yesterday, and just got gas bill emailed through for past 16 days - 1070kWh used! Seems a huge amount to me, and immediately had me questioning if something's wrong, but then we've been used to a well insulated flat for years before, and this is our first winter in a 3 bed semi (2 of us wfh, Wiser set up, certainly not extravagant with the heating!).
Makes me wonder what the usage would have been like without the Wiser kit. At least it's got milder of late.
This guy says you shouldn't lag your indoor pipes as can reduce boiler efficiency. Any thoughts?
. Any thoughts?
Yep. What he says is only really valid if you are trying to heat all of the inside of your house to the same temp. If you try to not heat spaces you aren't using, e.g. the basement with the boiler in it, storage rooms etc then insulating the pipes within those spaces or feeding them will be a good idea. The thermostat on your radiator only controls the water going through the radiator not the water going through the pipes feeding the radiator (assuming the radiator isn't at the end of a loop of course). So insulating those pipes will save heat from the pipes heating up spaces you don't want heated up
If you are heating your whole house to the same temp he is of course correct
Anyone estimated what they are likely to save on energy use yet? I've got a back of the envelope calculation running which seems to suggest that dropping from 19 to 16 degrees is going to save me 30% over the year. This sort of matches what I see on the web which suggests 7-10% per degree but given the sorts of monitoring people seem to be doing here I'm sure others have estimates running as well so I'm interested to see what you think
Ours is already at 16°C and as I keep telling my wife, IT ISN'T CALIBRATED so probably doesn't click on at a real 16. And being in the hall, is probably in the coolest place in the house which means it probly stays on longer than if it was somewhere else.
If I reduced it further, it might never come on... 🤔
As long as I use less than last year and reduce our usage I am happy enough. With the recent cold spell I am not so sure but we will see, our heating is off from May/June to partway through November anyway as the temperature is stable throughout that time.
I keep forgetting to take daily gas readings to check up on our usage, I only have the Nest daily usage figures which got up to 3 hours a day on the most coldest days. I've also now reduced the flow temp to 60c ish. I'll reduce that further on the warmer winter days to see how it goes.
This guy says you shouldn’t lag your indoor pipes as can reduce boiler efficiency. Any thoughts?
Your rooms don't all have the same heating requirements. Our kitchen and hallway are cool due to the doors, floor and the fact it's on the ground floor; but the living room above them is fine. Unlagged pipes in the ceiling void put heat into the living room where it's not needed instead of the kitchen where it is.
As for boiler efficiency - you do need to be able to dump enough heat to have a low return temp. But unlagged pipes are the same effect as slightly larger radiators, except you can't control where the heat goes.
As always - it depends.
Just received Decembers bill, £800 for the month. Wife thinks that’s not too bad. What planet is she on? That’s more than my annual bill used to be.
Just received Decembers bill, £800
As of midnight yesterday, we'd used £186.59 in total for Dec. I'm crying as I type this as we've still 6 days of usage to go.
800 quid. Does your wife like to wander round in her smalls? Or is your house very poorly insulated (like my new crappy installed but very expensive windows so I expect a similar bill but not generating underpant friendly conditions)
If it's anything like.my in-laws....
They turned the heating off at 10pm last night - it was about 1 billion degrees . - they don't have a thermostat.
It was -1 outside.
We all woke up cold this morning.
I suspect they have the sum of **** all in the way of insulation anywhere......
their heating bill will be similar I'm sure...
Just received Decembers bill, £800 for the month. Wife thinks that’s not too bad. What planet is she on? That’s more than my annual bill used to be.
Does she have a job?
Sister in law is a stay at home mum and spends money like water, she has absolutely no concept of money / value / worth and pisses her other half's salary up the wall playing keeping up with the other stay at home mums in her social group. Both kids are at private schools and not actually at home...
Mine has come to 320 split almost 50:50 gas and electric. Considering they were demanding 450 in DD payments before I cancelled it, I'm pleased its not as high as I feared, but unhappy that its as high as that.
I've not had an opportunity to compare kWH consumption with last year though.
Actions this year so far are dropping ambient temp from 20° to 18° on the stat, wearing jumpers, and reducing flow temperature of our boiler from 60° to 47°.
We also turned off a few more standby gizmos and changed how we dry our clothes from forced electric heating to standing next to the living room rad where there is heat anyway.
Ours is sitting at £320 for the month today
For anyone with a smart meter wanting a decent running comparison I find the U Switch app really good.
Much better than the BG one (I'm with them for both gas/elec) weirdly its almost like BG want to keep up by having an app but don't actually want you to have any idea of how your consumptions compares by day/week/month/year
Do we need some perspective… If you’re in 300sq ft detached in Scotland you’ll be spending more than a 100sqft terrace in London (probably)
I’ve no idea what mine is. They Only do bills every 6 months and I’m not on a smart meter. Apparently you can’t have smart u16’s.
reducing flow temperature of our boiler from 60° to 47°.
That's pretty low. Do you not get short cycling?
Re our £800 bill, we’re in a 1930s 4 bed detached with poor insulation, 1 year olds twins and obviously it was pretty cold recently. I WFH but I’m happy to wear extra layers. She won’t let the thermostat go below 16.5 overnight because of the children. She also sees the heating as a first resort, whereas I’d only put it on if I were desperate. I stil can’t believe she thinks it’s a reasonable figure, but I won’t raise it with her, it’s not worth the argument.
Went to friend's house for Xmas dinner, I thought it was summer by comparison to my flat. LOL!
The temperature never went below 17c and was 21c to 23c (think he set it to min 17c and max 23c) during the evening; and I was actually sweating. LOL! Told me his gas bill was around £250 per month excluding electricity but told me electricity was about 1/3 of that. 3 beds old house, used to have the toilet outside, with minimum insulation. I guess the heating bill must be the norm for old houses?
That’s pretty low. Do you not get short cycling?
No, I switched the boiler a year ago to one that will modulate down to 1.5kw. I alao have quite large radiators.
I get lovely base line heat and almost absent steam from the flue.
My bill is for 121m2 1980, 3 bed detached.
C250 here for whole dec in a detached bungalow min 14 deg max 18. Elec 50gbp gas 200gbp.
Combi on 24 7 I turn it down to c12 at night on 18 all day. Effectively just topping up lost heat during day.
New roof and breathable membrane last year so no drafts up there.
Pretty pleased tbh as it was -10 mid Dec.
It's on and off when I want it to be; thermostat is programmable but I use manual over-ride.
Fully acknowledge that I'm very fortunate in being able to absorb the extortionate energy prices when so many others cannot.
Heating still off. I have a log burner on the go most of the time and a pretty consistent 17 degrees through the day. I cut and sort all of my own wood, but as we are an end terrace 1900 build I reckon we are as low as you can go. The gas is sitting at about £80 pm so not doing too badly.
Ummm.
You know a log burner is heating right?
Which is less bad from efficiency perspective- low temp and cycle more or high temp and cycle less?
Pretty similar to you Edward- I keep the kids bedroom warm in the night in the vein hope it helps them sleep better!
Not sure I follow the connection between short-cycling and lower temperatures; surely short-cycling is a function of thermostat offset, rather than temperature?
I’m not sure either ..but if the temperatures are lower then the boiler takes less time to reach the flow temp and so then switches off, but if the room isn’t up to temp it then comes on again after not long and repeat. Whereas higher flow temp the boiler runs full tilt and room heats up quicker so maybe less cycling?
This guy says you shouldn’t lag your indoor pipes as can reduce boiler efficiency. Any thoughts?
Your rooms don’t all have the same heating requirements. Our kitchen and hallway are cool due to the doors, floor and the fact it’s on the ground floor; but the living room above them is fine. Unlagged pipes in the ceiling void put heat into the living room where it’s not needed instead of the kitchen where it is.
As for boiler efficiency – you do need to be able to dump enough heat to have a low return temp. But unlagged pipes are the same effect as slightly larger radiators, except you can’t control where the heat goes.
As always – it depends.
In short, boiler efficiency is sort of irrelevant compared to total heating system efficiency. Useful output is hard to calculate though since as above it's the heat transferred to the rooms you need heating
Not sure I follow the connection between short-cycling and lower temperatures; surely short-cycling is a function of thermostat offset, rather than temperature?
When a boiler is oversized for the heat that is required, or can't reduce its output adequately, the temperature of the returning central heating water is so hot that the boiler thinks it's done it's job and it turns off the burner.
This means the boiler can't get anywhere near its dew point for recovering latent heat, and maximising its efficiencies, and it will need to fire up again fairly shortly because insufficient heat it lost from the rads into the room due to the short burn time - you get repeating firing events which adds wear and tear into the boiler.
No, I switched the boiler a year ago to one that will modulate down to 1.5kw. I alao have quite large radiators.
Nice. I can't splash for a new boiler currently but bigger rads might be on the cards in some rooms. I figured that the efficiency gains from a colder return temp would not pay for a new boiler very quickly.
Not sure I follow the connection between short-cycling and lower temperatures; surely short-cycling is a function of thermostat offset, rather than temperature?
Muddyjames has it right. There are two reasons for short cycling. One of them is as you say - if the on and off temp of the thermostat is too close then it will be short cycling.
However in the other case, if I set my flow temp to 50 then the rads are at 48 or so. The heat output of the radiator is therefore lower so it takes longer for the room to hear up and the stat to switch off. Ideally, the boiler would heat up the circulating water to 50C and then turn itself down so that it stays at 50 and the return temp at say 30. But for that to happen the heat input of the boiler has to equal the heat lost by the radiators. When they are at 47C the heat lost is lower so the boiler has to turn it's flame down to match that. But many boilers can only go so low. Mine has a minimum of 9kW so 9nce that 50C is reached it has no choice but to switch off. The flow temps then drop towards to the return temps. But because my boiler is shit, it sees the temps drop and goes "oh, better start up again" within a minute or two.
The only way to stop this is to increase the flow temp so that the rads can dump 9kW of heat, or fit bigger rads so they can dump 9kW at the lower temps. I can increase the flow through the rads to make them hotter, but whilst they emit more heat, more heat is going into them to begin with, so the return temps are higher. The boiler is simply adding to the return temps, so it reaches its target temp more quickly! And then the return temp is higher so it condenses less well.
When it was cold, the rooms would not heat up fast enough so I had to set the flow temp to 60C. The cold weather didn't mean my radiators were dumping more heat since although it was -4C outside it was still 16C inside just as it is when it's 10C outside. It did mean that they needed to run for longer though, and more frequently.
Now that it is warmer, I could turn the flow temp down, but that makes it take longer to warm the room. I have to position the thermostat so that it will warm up and switch off before the flow temp exceeds the set value and it short cycles. But if it shuts off too soon in the hallway the other rooms have not got up to temp!
So I have to adjust the flow temp, flow through the hallway rad and the distance from that rad to the stat to keep the return temps as low as I can whilst avoiding short cycling and giving the other rooms time to warm up!
When a boiler is oversized for the heat that is required, or can’t reduce its output adequately, the temperature of the returning central heating water is so hot that the boiler thinks it’s done it’s job and it turns off the burner.
Mine shuts off based on the flow temp not the return. Mine is still condensing, with the return temps slowly climbing to 42C or so because the flow tops out at 65C. If I increase the flow temps then the room heats faster so no short cycling, but the return temps are 50C or 55C. So it's a toss up which is less efficient - short burn times or higher return temps.
It also matters what temp the stat is set to Vs the TRVs in the rooms. If they shut off, then the system can dump far less heat so short cycling is more likely. But the rate of heat loss is different for different rooms, but the heat input from our activity is the same, so when it's colder I theoretically need different parameters to when it's mild. And when it's cold and the air has been heated more the relative humidity is lower in the house, so I need lower temps to feel comfortable and perversely higher temps in the house when it's mild.
Argh!
So many people buggering about with boilers and CH but none claim to be heating engineers.
Call me old-fashioned but I would stick with people who do this stuff for a living - aka 'experts'.
£390 for the month so far. £1700 for the year but it would appear most of that is the past few months.
‘’So many people buggering about with boilers and CH but none claim to be heating engineers.
Call me old-fashioned but I would stick with people who do this stuff for a living – aka ‘experts’.’’
With all due respect I really don’t like attitudes like this. And it’s common in many formats. People are just trying to help themselves a bit and share new found knowledge. You don’t have to be a mechanic to diagnose a flat tyre.
I reckon we’ll be on ~£220 for December including wood. 3 bed, mid terrace, solid wall 1880’s build. Thermostat at 18 daytime and 14 nighttime.
I used to think it was pretty inefficient but this thread has changed my mind dramatically. Even in the really cold snap with -5 overnight we were only loosing ~3 degrees overnight, on normal nights it’s more like 1.5 degrees.
Call me old-fashioned but I would stick with people who do this stuff for a living – aka ‘experts’.
You are old fashioned. A lot of 'heating engineers' are people who were just fine with boilers when they were just an on/off thermostat and that was it but they struggle with modern heating systems where you have to estimate the thermal mass of your house in order for the control system to work. On a similar theme I just had a quote for solar panels but the 'expert' completely missed the fact that our house requires a three phase inverter rather than single. The person who proposed our underfloor heating didn't want to insulate over the concrete beams because 'heat goes up you know'. It never hurts to do a bit of research yourself. I would love to believe that everyone in a profession is an expert but it really isn't true.
but the ‘expert’ completely missed the fact that our house requires a three phase inverter rather than single
What makes it require a three phase inverter ? Are you hooked up to all three phases in your house. That would be very unusual.
What makes it require a three phase inverter ? Are you hooked up to all three phases in your house. That would be very unusual.
It is unusual but i am. The oven is on all 3, various other parts on the house are on different phases. I have to add though that i am in Brussels and we are a bit unusual in that not only is it 3 phase it is 3 phase delta.
With all due respect I really don’t like attitudes like this. And it’s common in many formats. People are just trying to help themselves a bit and share new found knowledge. You don’t have to be a mechanic to diagnose a flat tyre.
Yeah, My friend was complaining about heating prices, I tried explaining a bit about flow temp, told him about the heat geek YT channels (hes an avid YT watcher)..and he's like, my boiler only has one dial, not seperate ones for water and CH... I was like really? you sure.. he went to look... "oh yeah, there's 2 dials".
I said turn your hot water down to 40c (combi/condenser boiler), there's no point having scalding hot water comming out of the shower head only to have to mix back down with cold.
The response? "nah, I can't be bothered messing about with it"
He literally has no idea how to use his boiler and doesn't seem to care, but does care about his high bills ¯\_(ツ)_/¯
Equally, wallking around my neighbourhood the other day having a nose at peoples flues - the number of houses with huge plumes of steam errupting from them was staggering.
That flow temp pointer above is one of the most useful things I've ever read on here!
I never though about it before but I always mix down the shower with cold, just checked, the hots set to a scalding 60c, I've just wanged it down to 45c and I'll go from there
Thanks!
^ that's OK if you have hot water on demand but ours comes from a cylinder, and with daughter and wife in particular taking long hairwashing showers they can deplete the cylinder sufficiently that by the time son and then me get showers they're lukewarm or even cold
By having the water hot, they use less / cut it with more cold that is unrestricted supply and I've at least then got a fighting chance.
I might look at adjusting when she goes back to Uni and then adjust again when back, it would be interesting to see if it has any impact on bill / usability.
I’ve just wanged it down to 45c and I’ll go from there
You might want to put it a bit higher. I know that my boiler has a feature where if the water tank temp is as low as that for a few days then it will crank it up over 60 once to prevent legionella
Managing legionella in hot and cold water systems (hse.gov.uk)
I don't know how much of a real issue this is. I just know that my boiler has a feature to avoid this and also the link above. I also did some measurements over a few weeks with the temp set at 58 and also down at 45 and didn't find that I saved a detectable amount of gas. My tank is well insulated so it takes a couple of days to cool down on it's own so that may help.