Love or Hate your Combi Boiler - advice appreciated

tm9

Hi, this is my first post and I would really appreciate some advice from people with combi boilers.

We are looking to install a new heating system to a 4 bed 70's style house and are considering a combination boiler. There is currently nothing there so we will be installing everything new (radiators, pipework, etc).

We like the idea of the combi as the house has a very small airing cupboard with a tiny cylinder and we would not be able to fit a very big cylinder here. Also, we like the idea of using fresh water rather than water stored in a tank for weeks and being able to run a shower with it.

Looking around it seems that some people love combis and some people hate them. Really would appreciate some advice from people using these boilers (rather than people that are trying to sell them to us!). Has it been reliable, does it take ages for hot water to come through, is the pressure at the taps ok, does it take ages to run baths, do showers work well, would you recommend.

Many thanks

Cardew

WHICH has a good report on the pros and cons - might be worth reading.

It is not really 'love and hate' but a preference.

The time for hot water to come through is dependent on the length of pipe run as much as other factors. some combis have a small internal tank which you can use, or choose not to use.

Filling baths or shower output is obviously not as good as a tank.

My preference is a HW tank

tm9

Cardew wrote: »

WHICH has a good report on the pros and cons - might be worth reading.

It is not really 'love and hate' but a preference.

The time for hot water to come through is dependent on the length of pipe run as much as other factors. some combis have a small internal tank which you can use, or choose not to use.

Filling baths or shower output is obviously not as good as a tank.

My preference is a HW tank

Hi Cardew,

Many thanks for the info - the local heating company said it would be slower filling a bath but that a shower would be a lot better as it would be coming from the mains rather than a tank - I think you are saying that a shower would be better with a tank?

azzabazza

We renewed our boiler 3 years ago with a combi. We had it installed in the loft with a pressure guage in the airing cupboard.

Main dislike is it takes ages for the bath to run. Also have to run the kitchen tap a bit before the hot water comes through. However, the shower is fed from the mains and has better pressure than with the old boiler. We found the combi was more fuel efficient than our old boiler.

The above dislikes are actually just inconveniences when I think about it and you quickly learn to adjust.

My brother in law has his own central heating firm and he recommended a combi to us. He did not fit it as he lives too far away.

tm9

Many thanks for all the info. Just wondered whether the water still gets hot enough in the winter when the temperature of the incoming mains water is a lot colder than in the summer. Does it take longer before the water comes through hot at the tap? Sorry for all the questions!

Cardew

tm9 wrote: »

Hi Cardew,

Many thanks for the info - the local heating company said it would be slower filling a bath but that a shower would be a lot better as it would be coming from the mains rather than a tank - I think you are saying that a shower would be better with a tank?

Hi,
The arguments for and against combis have been rehearsed in many posts in MSE and other forums.

The main limitation of a combi is an inability to heat sufficient water for a decent HW flow - particularly in winter when the mains water input can be around 3C; and especially if two outlets attempt to use HW.

You can check the specification of a combi flow - normally expressed as raising the temperature by xC at ylitres a minute(

Certainly a shower would be better from a tank if you want a high flow rate. For instance a 'power shower' (not to be confused with an electric shower) will only run from a tank.

Also the savings of a combi tend to be over-estimated. Modern well insulated HW tanks lose very little heat. They are tested to a British Standard and a tank held at 65C will typically lose between 1kWh and 2kWh over 24 hours - say 4p to 8p with a modern boiler. In practice the tank will not be at 65C for 24 hours.

In any case the heat is not 'lost' as it heats the fabric of the house; which is why tanks are often in airing cupboards.

An advantage of a combi is certainly that the removal of tanks make more space.

Own_My_Own

I have a combi. Have found it a lot better than having a tank. My bills have gone down by a fair amount. There is always hot water, so as many people can shower or bath as you need. On the other side if only one shower is taken no money is wasted heating unwanted water. Also we can go on holiday without having to muck about with timer etc. That is a small thing, but it's one small thing not on pre or post holiday to-do list.

inmypocketnottheirs

I have sold central heating systems and over 90% of the installs I sold were combis. Would I have one? Never.

tm9

inmypocketnottheirs wrote: »

I have sold central heating systems and over 90% of the installs I sold were combis. Would I have one? Never.

Why is that? Is there any other system you would recommend? We have a problem in that our airing cupboard is really small. The thick insulation on the latest new cylinders would only leave us with about 14 inches across for the actual cylinder and I am not sure where else we could locate it. However, if the combis are not good then I guess we might have to look in to this further.

Thanks so much for the info.

DVardysShadow

tm9 wrote: »

Why is that? Is there any other system you would recommend? We have a problem in that our airing cupboard is really small. The thick insulation on the latest new cylinders would only leave us with about 14 inches across for the actual cylinder and I am not sure where else we could locate it. However, if the combis are not good then I guess we might have to look in to this further.

Thanks so much for the info.

You could always slice the insulation off to get a cylinder into the space, although this is probably a criminal act or fraud or something these days

I have had both a combi and a conventional boiler in 2 different properties. The combi would be tolerable if it were not vulnerable to low water pressure, but there is very little about the concept which commends it over a properly installed conventional system. Running costs as far as I can tell across 2 properties are about the same

PaulF81

Unvented tank for me. Unless you get a big boiler, they dont give great flow.