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My external oil boiler is knackered and needs to be replaced. Trying to decide whether to just replace like for like with a new heat only one, or go for a combi boiler. Obviously a combi is a little more to buy and there’ll be some plumbing work required inside the house, but then they’re more efficient supposedly. 3 bedroom house with one bathroom and four sometimes five occupants.
What do you reckon?
Are you in a hard water area? If so, you might need a filter on the inlet which needs changing regularly. Just an extra running cost to consider. I have no idea how much they are.
Very soft water here
I'd stick to a system boiler if your hot water cylinder is ok as less to go wrong.
If it were me, I'd stick with a traditional cylinder but I would consider a complete overhaul if you have the space/money and go for a mains pressure system with a big tank.
In my last house we had a combi and the pressure would drop to a trickle if water was being used elsewhere (ie, washing machine, kitchen etc). This was compounded by our being on a shared feed with five other houses and ours was the last in the row so when other houses used their water it would effect ours - but I accept that is an unlikely scenario for the OP.
Need to try and keep the costs down at the moment to be honest, so I doubt I can redo the whole system. I can get the plumber to check the condition of the existing tank though.
The mains pressure here is enough to knock a small child off its feet.
Probably depends a bit on whether you're happy with the current water pressure for showers and if the existing tank is enough or if water runs cold from time to time. I switched to combi but it was a no brainer for me as the hot water tank was at the same level as the shower so without trying to pump it the pressure was crap. I also like knowing I don't need to worry about the hot water tank running cold - not that it did often but just nice to not worry about it. Only downside I can see is no immersion heater backup if the boiler plays up but I only used mine once in 20 years with the old system
Heat only all the time, no heating is manageable, not hot water is not fun.
Also heat only will be much cheaper.
Will there be much difference in oil use between the two?
I’ve got a combi, it’s shit. You have to turn the tap on nearly full to get it to kick in. If you turn it down too much you get a cold blast for what feels like ages until it kicks back in again. If someone else uses a tap the shower slows down. I assume newer boilers (although it’s only 15 years old) are better and kick in with lower flows.
I wouldn’t have one out of choice. A hot tank and pumped shower seem a much better choice.
I’m amazed at the lack of love for Combi boilers!
Ours is great (we’re mains has not oil, don’t know if that makes a difference).
What’s the point of heating a massive tank of water twice a day just on the off chance you might fancy a bath, or need to do the dishes?
I’ve not had a single issue with a combi in more than 10 years of having one. I don’t need to blast the hot water tap to make it kick in etc, it just works.
Gas bills pretty much halved, and I hear oil is expensive?
We moved from Gas combi boiler to oil heat only.
We have already said that once current boiler goes we will be getting combi.
Combi for me but I have an expensive one so I get a really good shower from it
Need to try and keep the costs down at the moment to be honest, so I doubt I can redo the whole system. I can get the plumber to check the condition of the existing tank though.
If you want to keep costs down don't go combi... you need to get best quality or you can be in for a world of pain/£££. We had boiler insurance and after it failed twice in 2yrs (from new when we bought the house) the cost went over £400/yr just on insurance so I cancelled. Now have a spare triple valve I change myself and buy a new one every time it fails and pisses all over the floor again.
Fitting my combi was around £3000 IIRC. I was i a hurry and the boiler was most of that and it was replacing a combi. Its a huge KW rating so pumps out a lot of hot water. I can't remember the numbers but with a needle jet shower its painful and a rainfall shower still blasts you not dribbles
If you go combi get one with a small built-in mains pressure tank. Should reduce the short cycling and give you hot water quicker. Short cycling of any machinery is detrimental.
I say keep the costs down, but I’ll probably still get a WB one! I was thinking more from the plumbing point of view.
We’ve got one bathroom and an en suite but both with electric showers. Hot water use is therefore the bath (every night, at least one), plus the bathroom and kitchen sinks. Can’t remember if the dishwasher is both or cold only. So it’s not massive demand I guess. Say I wanted half a sink of hot water for the pans, is that a bit shite with a combi boiler then? My hot water tank is in the loft so it takes a good 30-45 seconds for the hot tap to run hot sometimes.
But I can’t be doing with stuff breaking regularly either. The old Grant one that’s finally given up (tank rusted through) is about 25 years old and apart from a clean up every few years it’s been fine.
What’s the point of heating a massive tank of water twice a day just on the off chance you might fancy a bath, or need to do the dishes?
Modern hot water tanks keep the water hot for a couple of days, not a few hours.
Mine’s covered in some green foam, rather than a puffa jacket - is that fairly modern? 😀
New combi should be OK given the size of house and use you suggest. Borderline though, and if you were looking at extending in the future I'd stick with a system. And if the plumber is blagging you for the cost of switching to combi tell them to sling it. Conversion from system to combi is a piece of piss, literally cutting a couple of pipes, capping them, re-connecting hot and cold and joining the rest together - seriously, couple of hours work tops in most cases, whole installation done in a day. Removing the system stuff then maybe there's cost there, but it's nothing you can't do yourself at a later date.
Plumber’s a mate so no issues on that front.
What’s the point of heating a massive tank of water twice a day just on the off chance you might fancy a bath, or need to do the dishes?
This is wrong. You're not heating a tank of cold water twice a day. If you're using all the hot water every day then your tank is too small. You're topping up the temperature of already hot water which uses very little energy. Also the tanks are super insulated so if you don't use any water one day it stays hot and ready for use the next day or might need extremely minimal topping up.
It's all about the situation and hot water usage as to which solution is best for you.
Modern combi boilers are extremely efficient too but are more complicated devices and more sensitive to the rest of the system...I know of people who've had problems and people who have not had any problems. And talk to ten different plumbers for their opinion and you'll get a decent split.
Either way you're much better off investing in a decent Branded boiler so if you're on a budget and assuming the rest of your system is in good nick then you are probably better off just replacing the boiler for as good a branded/quality one as you can. Doesn't really matter if its a combi or a system boiler at the end of the day.
And whatever you do install a magnetic filter if you don't have one already.
Or go full Stoner with solar, ground source heat pump and a thermal store
The only reason plumbers recommend system boilers is they make a fortune installing them. Extra tanks, stats, valves, control boxes, pipe runs. That's all good work to a plumber, and loss of amenity in your house as you lose cupboard or loft space to them. Then you have to chase in, box in or otherwise hide the extra pipes and wires. You've then got upwards of fifteen new points of failure.
Get a combi and an electric shower as your backup. WB, Vaillant or Baxi. Pick the right one and you'll have a seven or more years guarantee out of the box, and an option to extend or go to a simple maintenance and repair contract. To me it's an absolute no brainer. People say too you can't have a combi for bigger houses. I'm sure that's true for Downton Abbey, but our three storey Victorian place is perfectly fine with one, we used to have a combi with a built in tank, but switched to a regular Baxi last year. Hot water comes about a second slower than before, but gas bill has gone down. Shower on top floor is perfect, like a good hotel shower. Hot taps run at very nearly the same rate as cold. I guess it being oil has issues I know nothing about, but as with everything else, keeping it simple usually pays off.
The only reason plumbers recommend system boilers is they make a fortune installing them. Extra tanks, stats, valves, control boxes, pipe runs. That’s all good work to a plumber, and loss of amenity in your house as you lose cupboard or loft space to them. Then you have to chase in, box in or otherwise hide the extra pipes and wires. You’ve then got upwards of fifteen new points of failure
Maybe for a fresh install but for me the quotes I had for both types of systems were largely similar, certainly not large enough to lead the decision (replace and move location of boiler - so combi vs conversion of vented to unvented system) and ... additional cost of combi boiler mostly made up for additional cost of new tank - pipework was dirt cheap as existing pipework was largely re-purposed. Both required similar manhours to install and decommissioning the existing setup.
Had a few minor issues since the system boiler was installed, not with the boiler...but all fixes were cheap in terms of parts, I've been able to do myself with minimal hand tools and typical amateur DIY knowledge (with support from this forum and YouTube). If something goes wrong with a Combi system more often than not you're straight into the need for a Gas Safe plumber as the issue is more likely to be inside the boiler - and even with my fairly advanced amateur DIY skills I wont touch anything inside the boiler casing. So swings and roundabouts. Like I say depends on the house size, configuration and number of people in the house and how they use hot water.
Every installation is unique...no single 'best option' for every home, and influenced as much by how people in the house want to use the system rather than what's technically the best system on paper.
The only reason plumbers recommend system boilers is they make a fortune installing them. Extra tanks, stats, valves, control boxes, pipe runs. That’s all good work to a plumber, and loss of amenity in your house as you lose cupboard or loft space to them. Then you have to chase in, box in or otherwise hide the extra pipes and wires. You’ve then got upwards of fifteen new points of failure.
That's not really true though is it? Combi boilers are good and can often be the best solution but for a great many situations they are woefully inadequate. Say for example a larger house with two or three bathrooms, someone who wants to have a power shower or a house with low water pressure.
Say I wanted half a sink of hot water for the pans, is that a bit shite with a combi boiler then?
In theory no, if your piping is efficient.
but ...
My hot water tank is in the loft so it takes a good 30-45 seconds for the hot tap to run hot sometimes.
so it will require some re-piping, it's a question of how efficiently the new piping can be done.
I'd also assume at some point you might want to use replace electric showers etc. and go up with capacity and as I said earlier quality is more important on a combi.
It's not just no heating.
Whichever nob-end fitted ours hadn't put a stop-cock before the cold inlet so every time it blew the triple valve it was no water at all. (I now remedied that now)
Yep, but thegreatape already told us he has water cannon pressure. As for the big house argument, try mine, seven bedrooms, two and a half bathrooms three ensuites. Power showers not necessary with great flow rate and good pressure. Also it's a family home not Ramada Inn. If more than three want a bath or a shower at the same time, how big a deal is it really to wait a couple of minutes? As for heating, well it just works as they say, got to be better than feeding the 10 coal fires like when the house was built. Factor in that many people can't or won't operate anything more complicated than a single TV remote (You have to switch the source to HDMI2, been there?) and in all likelihood you're putting off buyers if you're planning to sell up. Where in real life, for homes not hotels or nursing homes are these situations where combis are woefully inadequate? Adding wet solar and PV is on our list for next time, and will need a heat store for that, but for straight fuel to heat, keep it in one box.
had an external oil combi fitted 6 months ago, had nothing before that. went WB which wasnt cheap but none of the external ones are. one thing is which i didn't know about at first is that they work slightly differantly to gas combi's and need a controller that times the hot water on/off. its not an issue though as ours goes off at 9 and after a night bike ride it still provides enough hot water for a shower a few hours later even though its off.
n my last house we had a combi and the pressure would drop to a trickle if water was being used elsewhere (ie, washing machine, kitchen etc).
I think it tends to be the house pipework capacity that tends to be the limiting factor. When we had our extension the new combi0-boiler got plumbed in on it's own dedicated pipe from the mains coming into the house, so turning on cold water elsewhere in the house doesn't have any noticeable impact on the combi output.
Adding wet solar and PV is on our list for next time, and will need a heat store for that, but for straight fuel to heat, keep it in one box.
PV is great (no ideal about wet solar as we don't have it but it's a one trick pony) - but putting everything in one box means you lose everything if it goes wrong.
A combi and a heat store doesn't seem to make sense tbh.
If I were in the OPs shoes I'd replace the system boiler and, when able to, replace the existing HW tank with a used megaflo off eBay.
If I replace like for like will I notice a difference in oil consumption between the 25yr old leaky one and a brand new Worcester Bosch one, for example?
You'd certainly hope so - but I have no idea!
Love my combi. I assume lots are undersized to have issues with showers etc - can have ones now that will support a couple of showers and other usage at the same time.
If you can use a time of day tariff like Octopus Agile I can see the appeal of having a hot water tank with immersion - use a smart switch to heat it when power is cheap.
Say for example a larger house with two or three bathrooms, someone who wants to have a power shower or a house with low water pressure.
I've solved this problem by having two combi boilers*
One for upstairs, one for downstairs. Works remarkably well
* A legacy of restoring a previously split house back into one. It's not a strategy I would recommend unless you had to do it.
I’m with @P-Jay when it comes to the combi. We have a Worcester Bosch supplying a four-bed two-bathroom house with up to ten occupants, some of whom are teenagers who love their showers!
It’s been faultless for at least five years so far.
After an adult lifetime of living in houses with combi boilers and on demand hot water with dribbly electric showers the house I'm moving into in 5 weeks has a hot water tank and power showers. As a couple with erratic habits of comings and goings set to fox any timer I am rather dreading the endless "is there any hot water?" or "I put it on 15 mins ago so just wait 15 mins" faffery I remember growing up around washing of dishes or people. I am however looking forward to proper shower again though!
Unvented tank will solve those problems
When ours goes pop I shall replace with conventional. I know of 2 people that had problems with combis during cold winters and had to wait a couple of weeks to get fixed.
At least with conventional you can use the immersion heater for hot water.
At least with conventional you can use the immersion heater for hot water.
And with my propensity to forget to check the oil, this cannot be overlooked.
If you've not got multiple bathrooms then a combi will be fine. Even if you have, there's options for combi with buffer tanks etc.
I'm moving from a combi to a system with heat exchanger store (unvented tank, mains pressure) following recommendations. Slightly more initial install, but provides more flexibility over future usage and will allow for incorporation of solar PV in near future.
I’d stick with heat only. Had a combi in my previous house, always losing pressure and problem after problem. Much more simple system with less to go wrong heat only. I Like having a hot tank of instant water. Nice having an effective airing cupboard and seems no more expensive to run even though it’s an old ancient boiler and the house is twice as big