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Looking to replace the combi boiler in our lower conversion. 4 bed, 2 bath (showers fed via boiler), approx 2300ft total. I want to go with another combi but not too sure on KW output and make, hence looking for suggestions. The house, being Victorian is not particularly well insulated and we cant do anything about that hence the boiler generally operates on its lowest setting for a fair amount of the day. The current Potterton is a 28KW which certainly could not handle two people showering at the same time. Thoughts and suggestions pls
Not a combi!
If you do, a 40+kW combi, but be warned it may need a big gas pipe if it is far removed from the meter.
its got to be a combi, connecting a tank would be too much hassle.
Why would a mians pressure cylinder be too much hassle, you could even conect one to your existing combi?
Bear + 1
Unvented all the way. No header tanks. Easy.
at a push, thermal store, especially if you want to dump other heat sources into it.
space unfortunately. I have the space that a combi takes up to put a new boiler in....
I had a new one fit approx 18 months ago, after much research (I am a research junkie) I went for Worcester Bosch combi. 37cdi. They do bigger.
Why WB, simple. You can read as many forums and as much as you like, I took the view it was likely any new boiler was probably going to give me some grief at some point. WB have a call out team bigger than all others and offered a 7 year full warranty, unlike anyone else. Yes you have to use an approved installer and you can get cheaper, but ringing around and a few quotes I got a good price a great company and 7 years warranty. Happy chap.
Note earlier comment re gas supply. My boiler Is quite a distance from the meter so I needed a new big bore gas pipe installing as well. It's adds to the cost, but if yr like me and research too much you,ll understand regardless of what some say without the right gas pressure / supply you've wasted your yr cash.
Vaillant 937. 37kW but with 15l (iirc) of boiley hot water stored to feed in as required. It can do 20l/min for 10mins ie enough for a bath or shower before it drops back to being a straight 37kW boiler.
It does 20l/min at 42 outlet (probably from boiler) so at tap or shower will be less. Showers temps fro blokes will be ok, women have much hotter showers and baths are usually hotter still therefore you will not get 20l/min out of it.
No location to put unvented cylinder, they can go many places? Or can you use one of the bolt on hot water units to a combi?
+1 for Vaillant.
We had a Vaillant Ecotect 831 (31kWh DHW supply) fitted two months ago, to replace a traditional 20 year old vented system in a 4 bed, 2 bathroom house. Having high pressure hot water is great and the showers are now enjoyable. There is only two of us in the house and we never have an issue with not having enough hot water as it supplies nearly 13 l/min, which is ok for our needs. This may have something to do with us intalling water restrictors on the majority of taps/shower outlets to ensure balanced/steady outflows.
We also have the weather compensator fitted which should make the system more efficient once the cold weather starts and the central heating is switched on.
As said in previous posts, we also had to have our gas supply from the meter increased to allow the boiler to function at max output.
You also need to check what energy requirement your house needs, because there is no point having a large combi, if it wont modulate down to a low kWh usage when you need very little heating. This causes the combi to enter an anti-cycling mode which affects its efficiency.
Interested in the bolt on hot water units so off to google that now. I've a WB about 35kw in an old 4 storey victorian house with a loooong run up and down, it won't handle 2 hot water outlets well at the same time and I'm gonna need it to asap. One shower or hot water flowing is fine, 2 and the later one gets next to nowt. I wish I'd put a mega flow in now but was told it would cope which it definitely doesn't. I no longer have the space to put a megalflow in now either ggrrr on the upside the WB has been pretty good.
there are companies that make slimline unvented units (Oso Ho****er)
no... choice really..
Worcester Bosch.. the sizing issues are around the volume of hot water you might need not really about rad numbers or sizes.
from your description i'd want min 30 kw no need to go as high as 40kw.
ask for a magnatec or fernox magnetic filter to keep the gunge out of your new boiler and you ll easily get the 7 yrs problem free.
since i became soley WB 5 years ago i havent had to repair one i've installed.
we re speccing the wireless rf control units on 90% of these installs and in the last 2 years have had no issues, the earlier models did lose communication but those isses have now been long resolved.
okay, space wise, we have a standard 600 wide , 560 deep, 2100 tall unit to house both boiler and if going down the alt. route cylinder also. Maybe a small mains pressure cylinder could go in there with a boiler, but I would guess it would be so small that it would empty too quickly - both showers have large diameter rain heads so use a fair amount of water. The current Potterton 28kw combi job is absolutely fine for one shower running but in a few years the kids will be having showers as opposed to baths so it makes sense for the new boiler to allow for some future proofing.