Combi vs traditional boiler

[lolalotta]

Hello, we have moved into a 1920s 4 bed detatched house with two bathrooms, an under stairs loo and a utility room. The boiler looks really old, SSE refused to service it as they can't get into it properly because of the way the previous owners have boxed it in. Apparently the shower in the master bathroom has a pump (I don't really know how all that works but the pressure is low when one of the kids turned it off by mistake) The shower in the ensuite is an electric shower with very little power. My question is that I think we need a new boiler and I don't know if we should be considering a Combi or not? (We have a traditional tank in the airing cupboard at the mo) We have a plumber booked in tonight to chat it through but I would like to have a bit of a clue before we head into this! Does a Combi work if you have a shower with a pump? A friend mentioned maybe not?

Hello, we are replacing the flooring on the ground floor of our house. Re-plastering too, wood burner being put in etc so lots of work. The skirting will be removed so we are considering placement of sockets carefully, also all the radiators are being replaced and a new radiator put in the extension (I'm hoping the pipes for this can go under the floor but really am clueless and am waiting to chat to the plumber about this) My question is, is there anything else we should be considering/ thinking about before we do this so afterwards we don't have a "bother we should have done that before the new flooring went down" moment! Thank you!

Sorry people that was meant to be on a separate thread....

Not a direct answer to your question as I don't know much about gas boilers but have you looked into changing it for a renewable energy source since you're changing it anyway. We changed our oil fired boiler for an air source heat pump. It's economical to run and we get about £1400 per year back through the renewable heat incentive payments. You need a suitable outdoor space with a few metres clear in front of it but that's all. Whereas ground source heat pumps and biomass boilers both need a lot more in terms of space. It works best with underfloor heating but will work on radiators too although you will need to oversize them. If you're going to be pulling up floors anyway, it might be worth considering installing underfloor heating. Just an option to consider.

Ps ours is also an older house - 1930s. We put underfloor heating in the downstairs extension and replaced the radiators with triple thickness ones in the main downstairs rooms when we had the heat pump installed.

You won't be able to use the shower pump with a combi, but with a combi boiler your hot water will be at mains pressure so you shouldn't need it. That assumes you have decent mains pressure (what is the pressure like on your kitchen cold tap - that is normally connected directly to the mains).

Whether you can run two showers off a combi boiler simultaneously is tricky to say - some people say you can, some say you can't. When I was researching for our extension recently I decided against a combi for this reason (and the architect had already for a separate tank).

We've just had a traditional boiler replaced with same but a pressurised cylinder - we had the space to keep loft tank and cylinder (Victorian 4 bed house). The pressurised tank will allow a mains shower (hot water pressure now much better) as we removed the crappy electric shower.

A combi wouldn't have been suitable due to different demands for water (two toilets etc.).
We also considered air source heat pump but very badly insulated house and this would have been much more expensive.

We had several plumbers round who all had slightly different opinions (originally we wanted system boiler to avoid tanks but persuaded against this) so is worth assessing this as well as costs.

A combi boiler can only do one job at a time so in a house with more than one bathroom and water pressure issues it would be useless.

To get a good flow of water without a loft tank, it is likely that you will need to run a new, larger water pipe out to the meter or stopcock under the pavement.

During your other building work is a good time to do it.

Two things you should do today:

Fill a bucket at the cold tap at your kitchen sink, time it, calculate litres per minute. Repeat the test at your garden tap and utility room tap if you have them. The maximum amount of water that the old water pipe delivers is the limit that you can get out of all your taps, showers, appliances and WC cisterns at any one time. Consider how long it will take to fill a 100 litre bath.

Ask your water supplier to test your drinking water for lead content. There might be a lead replacement subsidy, or they may provide free or cheaper connection of your new pipe.

If your old pipe is steel, it may well be corroded and leaking, another good reason for replacing it.

With two bathrooms, you would benefit from a new pipe in 32mm or 25mm plastic. You will be amazed at the improvement in flow.

You could have a big combi if you wanted, or an unvented cylinder which will give you unrivalled flow for baths and showers, and the best option.