Slightly odd question that leads to a left-field suggestion - if you expect to be there for a good number of years, it’s worth considering a heat pump instead of a combustion boiler. You can get 400-450% output vs electricity consumed, meaning that your heat and hot water will cost (very roughly) half of current fuel costs, and you’ll also get a Renewable Heat Incentive payment from the govt - amount derived from your annual heat requirement.
The downside is cost, which is high by comparison: we paid just over £8.5k for a 9kW Samsung to heat our 3-bed semi, but our heating bills actually are less than half now and we get £800 a year from the RHI - total saving around £1400 a year or 15% return on investment…
Heat pumps are much more efficient when producing water at 40-50 C vs say 70-75 for a boiler, so they work well with under-floor heating. If that’s a step too far then larger or fan-equipped radiators could be a reasonable compromise.
Might be worth checking out with a renewables specialist.
if british gas condemned a boiler I would be getting a second opinion . they have outrageous prices for fitting new boilers and no doubt hope you go to them .
OK, story time and and new boiler advice needed…, or, “I need an adult”.
I’m finally in a position to do a new bathroom project which is significant as it acts as a catalyst to cascade a few other projects including a new boiler.
There are two key requirements
The shower must be mains fed. We have good water pressure and I want a good, powerful shower.
We currently have a floor-to-ceiling cupboard in the bathroom which contains both a hot water cistern and an old gravity-fed water tank. I want these gone to reclaim the space - either by means of a pressure tank(?) in the loft, or completely by way of a powerful combi (something like a Greenstar Classic 38CDi??).
If the boiler is being changed, I also want to take the opportunity of replacing the rads in the current central heating system. It will not be cheap as we have 18 (I think), but the current ones are inefficent and don’t have thermostatic control etc. I want to put in fancy controls (Nest or similar) at the same time.
We wanted a mega flow type system in our house but we didn’t have the necessary height in the attic to accommodate the unit. We have ended up with a sealed system (was vented) and a small highly efficient boiler. The upstairs bathrooms have pumped hot water and the shower is plenty powerful. Before we had all this done the heating was inefficient and the top rooms in the house suffered from a lack of pressure in the system. The shower was pitiful. I think with a mega flow you won’t need a pump.
We thought of changing the radiators but were advised not to bother, this has turned out a decent decision. We had the system flushed through and have subsequently fitted a water softener. We run Hive (@A_Touch_of_Cloth so shoot me! ) which we find very good and I am not sure whether thermostatic controlled rads would have been worth the extra expense and mess. The plumbing here works very well now, although I would still go for a mega flow I think, if we had the choice.
Bear in mind the gas supply. Most older systems have a 15mm input to the boiler. Powerful condensers will need 22mm min feeds so think of the connectivity route. You will get thermostats on the new rads which is good.
I bet @A_Touch_of_Cloth will be pissing himself with our attempted help though.
Best advice I have seen from him - get a price from BG (can be done anonamously on line) and aim to halve it.
You need to consider your hot water usage. If a single bathroom then a good combi boiler will be adequate. If you have an ensuite then standard combi will struggle unless you manage shower times and durations.
Secondly you need to consider what you currently have, in terms of incoming mains pressure and flow.
If you only have a 15mm incoming supply with 14 litres a min you will struggle with an unvented cylinder and throwing in a 40kw combi is pointless. Good practice dictates upwards of 18 ltrs a min for a cylinder and 22mm supply.
Also, don’t be surprised how quickly you can use hot water from cylinder if you have sprogs and a single bathroom with everyone bathing and showering one after the other.
Bear in mind if you go for a high powered combi, the gas as Mick mentioned, and where the boiler will be located in relation to the gas meter. You will be looking at 28mm pipe minimum for a 40kw boiler to ensure gas rate which bumps up price. There are high flow combis on the market. Worcester do one imaginatively titled "Hi Flow.
Dunno where you are located, but I would have thought around £150 ish to supply and fit a standard rad.
In a nutshell? Fucked if I know, without looking at job. A good local guy will sort you I’m sure.
I really want a Nest-type heating management system, but the thermostat on my boiler (a Worcester Bosch combi) is so good that I just can’t justify it - the temperature is always just right. Fucking annoying really.
The correct course of action is to post your question on every HiFi forum to ensure you get drawn up into long protracted discussions with diy donuts.
Also worth mentioning that if you go to a combi your system will be pressurised. Therefore if pipework is ropey be prepared to upgrade that also.
If your system is vented with gravity hot water cylinder it may be the best option to install a heat only/system boiler so your heating will remain vented with mains pressured hot water cylinder. Thus negating pipework issues and minimising gas issues.
All this is being written while waiting for a pair of cheese pasties from Greggs.
One bathroom you say? Good combi would be my instinct.
Can’t think of any other pitfalls you need to be aware of.
