Grant Vortex Oil Boiler fault, CH stops when HW is running?

[Nihad]

Hi all

We have Grant boiler
It never bothered us before but i’m curious to know whether this is a fault or normal for Grant boiler central heating to stop when the hot tab is running?
Also when the hot tab is off then it takes CH 5-10 mins to come back on

Any suggestions much appreciated

Thanks

 

[RandomGrinch]

Is it a combi?
It is normal for a combi!

 

[Nihad]

Is it a combi?
It is normal for a combi!

Combi yes.

 

[RandomGrinch]

Combi yes.

As above, a combi can only supply heat to hot water, or heating; not both together.
If you are used to having a separate hot water tank, it may take some getting used to, but it isn't a big deal.
I.e. to get around the limitations; putting the heating on for 20 minutes before having a shower, would be a good idea, for a comfortable bathroom temperature.

 

[ericmark]

I had not realised it turned the CH off, in the main oil fired central heating combi boilers don't give instant heat like gas ones, as in the main they don't modulate, so there is a water store inside the boiler, which has priority.

 

[RandomGrinch]

I had not realised it turned the CH off, in the main oil fired central heating combi boilers don't give instant heat like gas ones, as in the main they don't modulate, so there is a water store inside the boiler, which has priority.

Good point Eric. Apologies, my post was a little simplistic - the transition between firing for heating or HW supply may be more, or less noticeable, depending on the size of the thermal store.
The diverter valve will always give hot water priority.

Although, I should really have asked the question - has the boiler always behaved this way?

 

[Exedon]

Normal behaviour its how it works.
There is no diverter valve on a Grant combi uses 2 pumps.
On hot water demand flow switch operates hot water pump starts, when temperature of heat store drops burner fires.
When flow switch closes pump/burner will continue until heat store thermistors are satisfied.
Burner will shut down pump continue to run for around a minute. After that is there is a heating demand heating pump and burner will operate.