Combi installed for hot water, central heating added later?

[f0rmula]

We're living in our house, while renovating it. We're looking at getting our system boiler replaced with a combi boiler. Renovations include removing the airing cupboard, and refitting all the current central heating system, which might take me a while. It'd make my life a lot easier if I could get the new boiler fitted to provide hot water, and then add the central heating at a later date (before winter ). Is it possible to use a combi boiler for just hot water with the central heating in/outs disconnected?

If not, and the boiler needs water in that part of the system to avoid damaging it, how feasible is it to just add a temporary single radiator?

Cheers!

 

[dcawkwell]

No there needs to be a loop of pipe between the central heating
flow and return for most combi boilers.
But this is trivial to arrange so go ahead install the combi fill up
and you will have hot water.

 

[D_Hailsham]

We're looking at getting our system boiler replaced with a combi boiler. Renovations include removing the airing cupboard

I know a combi boiler will save space, ie. airing cupboard and no tanks in loft, but have you checked the water flow rate and dynamic pressure as well as the anticipated simultaneous requirement for hot and cold water?

 

[doitall]

Have a look at Atmos and Intergas boilers, they can be used as a water heater while you install the radiators

 

[f0rmula]

No there needs to be a loop of pipe between the central heating
flow and return for most combi boilers.
But this is trivial to arrange so go ahead install the combi fill up
and you will have hot water.

Fantastic news. Thanks a lot. Girlfriend will be very pleased. Until about October, when it starts to get cold and I still haven't been arsed to fit any radiators.

 

[f0rmula]

We're looking at getting our system boiler replaced with a combi boiler. Renovations include removing the airing cupboard

I know a combi boiler will save space, ie. airing cupboard and no tanks in loft, but have you checked the water flow rate and dynamic pressure as well as the anticipated simultaneous requirement for hot and cold water?

We have very little space upstairs, so unless the pressure/flow rate is completely disastrous, I think we're really after a combi boiler. From what I can see I think we have very good water pressure. The taps in the kitchen seem to blast water out of the sink if turned on too much.

Is there an easy way to check pressure and flow?

 

[Agile]

Your gas reg installer should check the dynamic flow rate when he gives you a quote!

 

[f0rmula]

Your gas reg installer should check the dynamic flow rste when he gives you a quote!

Great. Thanks. I'll make sure he does

 

[D_Hailsham]

We have very little space upstairs, so unless the pressure/flow rate is completely disastrous, I think we're really after a combi boiler. From what I can see I think we have very good water pressure. The taps in the kitchen seem to blast water out of the sink if turned on too much.

Is there an easy way to check pressure and flow?

It sounds as if you are in a small house, possibly only two bedrooms with just a bathroom and a kitchen, so having two showers going at the same time is not a possibility. If that's the case, a combi will probably be OK. But do bear in mind that all water, hot and cold is supplied from a single source, the incoming cold water main. So flushing the toilet while someone is having a shower is not a good idea. The same goes for running the washing machine or washing the car with a hose (if that's permitted ).

As for checking flow and pressure. The simple way is to use a bucket and a watch with a second hand. Time how long it takes to fill say 10 litres and then convert this to litres per minute. Pressure really needs a pressure gauge, but you can get a good idea if it is adequate if you have a garden tap connected straight to the mains. Do the sink test with the garden tap closed, then with it fully open. Provided there is not a considerable difference in the flow rates, you shouldn't have any problem.

The sizing of a combi (kW) for hot water depends on the flow rate; you need 2.5kW for every litre per minute flow. If you have a larger boiler all you will get is hotter water.

The central heating output also need to be taken into consideration as most combi boilers produce much more than the typical house requires. Use the Whole House Boiler Size Calculator to find out your heating requirement. Then compare it with the CH output of the boiler(s) you are thinking of buying.

Ideally the required CH output should be below the max boiler output and well above the minimum output.

 

[gasbanni]

Doitall has given you the best answer, if you fit an Intergas boiler your installer can program it tell it its a water neater on the pcb as long as the gas, electric cold and dhw are connected hey pesto unlimited hot water and the heating side can be installed at leisure !!

 

[doitall]

Doitall has given you the best answer, if you fit an Intergas boiler your installer can program it tell it its a water neater on the pcb as long as the gas, electric cold and dhw are connected hey pesto unlimited hot water and the heating side can be installed at leisure !!

Who takes any notice of what I say Gasbanni.

 

[f0rmula]

D_Hailsham,

You're pretty much spot on. I think a combi will be fine. It was in the last house. I'll definitely try the bucket approach too. Simple, and indicative of my water pressure and flow. Really hoping for a decent shower, after having the useless shower since we moved in.

gasbanni, doitall

Thanks a lot for the replies. It sounds like it's pretty trivial to hook up most boilers for just hot water only, so I'm not sure I want to choose an Intergas boiler because it has a specific feature as I'll only be using it temporarily. If it turns out an Intergas boiler is the boiler for me, for other reasons, this'll definitely be an added bonus.

Cheers all!

 

[doitall]

How about two of the best boilers on the market.

 

[f0rmula]

How about two of the best boilers on the market.

Why the rolly eyes?

I haven't looked at which specific boiler just yet, and I said if they were the right boiler for other reasons, then I'd be considering them.

 

[doitall]

How about two of the best boilers on the market.

Why the rolly eyes?
.

I like them