Want to use domestic hot water whilst central heating pipes are capped.

[Crofter]

Hi,

I have a Grant Combi 90 Outdoor oil fired boiler, installed in 2004. I don't know if it's a Mk2 or a V3 or if it matters in the context of my question below.

I'm rebuilding/renovating an old house, and am about to start running new pipes for the radiators. I work 9-5, so this will be done during evenings and weekends and will take a couple of weeks.

If I cap off the flow and return pipes for the central heating just after they enter the building through the wall whilst I do the above work, can I still safely use the boiler to provide domestic hot water?

Grateful for any advice.

Thanks.

 

[ShaunCorbs]

i would say no

 

[Crofter]

i would say no

Thanks for your reply.

Why would you say no?

 

[ShaunCorbs]

Thanks for your reply.

Why would you say no?

as theres no water in the boiler (heating side) and theres no flow be like a kettle

 

[Crofter]

I see what you're saying.

What if I cut the flow and return pipes as suggested, and instead of capping them off seperately I connected them together?

Could I then fill the boiler via the feed loop and use the domestic hot water whilst leaving the central heating turned off?

Thanks.

 

[GasmanxxxR1]

If there was enough pipework to dump the heat it will work, maybe attach a small temporary radiator

 

[ShaunCorbs]

I see what you're saying.

What if I cut the flow and return pipes as suggested, and instead of capping them off seperately I connected them together?

Could I then fill the boiler via the feed loop and use the domestic hot water whilst leaving the central heating turned off?

Thanks.

dont know as i dont work on oil boilers but some (gas) ones require a min rad size the oilly lads should comment soon

 

[Crofter]

Ok. I could easily plumb in a small radiator if needed somewhere out of the way - thanks Gasman.

I'll wait for the oil guys to chime in like you say, and see if there are any other ideas too.

Thanks

 

[Best]

I can't see it being much different having the boiler not piped to the rads circuit.
Less water, less to need to expand.
You could just disable the heating side.
But I have never considered it before, nor had the need to do that.

 

[Crofter]

Quick update....

I've just spoken to Grant who make the boiler, and they've said that it's fine to cap the flow and return for the ch and carry on using dhw. They've also said there's no need to tie the flow and return pipes together or add in a radiator as a heat sink.

So all's well!

Thanks for your help.