Only have heating when hot water is on

[Ridgway132]

I have a Potterton Suprima HE 80, Honeywell Controller ST6300A, three way diverter valve and a wireless thermostat on water tank, the latter three were recently fitted by a Corgi registered CH Installer. On leaving the premises the installer said that we can only have the heating on when the hot water is on. Sure enough, selecting just the heating on the controller nothing happens. Soon as you switch the hot water on....bingo! Surely, this is not right. The three way valve (brand new & tested) just remains in the same position all the time.

An ideas?

 

[urakai]

on older systems this may be the case but on newish ones you should have a separate control for the heating. sounds like the wirings not quite right to me. have you got a room stat?

 

[Ridgway132]

on older systems this may be the case but on newish ones you should have a separate control for the heating. sounds like the wirings not quite right to me. have you got a room stat?

No, we don't have a room stat. All rads have TRV's except bathroom.

 

[JohnD]

Boiler only running when Hot Water is on is very common on older systems, and I don't see any problem with it. If you are in the house, why wouldn't you want hot water to be available? the cylinder stat will prevent the cylinder being overheated. Any slight heat loss from your well-insulated cylinder will contribute to the warming of the house.

No, we don't have a room stat.

 

[Ridgway132]

Boiler only running when Hot Water is on is very common on older systems, and I don't see any problem with it. If you are in the house, why wouldn't you want hot water to be available? the cylinder stat will prevent the cylinder being overheated. Any slight heat loss from your well-insulated cylinder will contribute to the warming of the house.

No, we don't have a room stat.

It becomes a problem when the hot water reaches the desired temperature. When that happens - no heating

 

[JohnD]

It becomes a problem when the hot water reaches the desired temperature. When that happens - no heating

Are you sure? You said earlier "Sure enough, selecting just the heating on the controller nothing happens. Soon as you switch the hot water on....bingo!"

If what you now say is correct, then it's wired wrong

 

[Ridgway132]

It becomes a problem when the hot water reaches the desired temperature. When that happens - no heating

Are you sure?

Then it's wired wrong

Yep, sat here in the house with both CH and water on and its very cold...brrrr!!! but water tank is lovely and hot. Shame I can't move computer into airing cupboard. I think its best if I get the guys out who did the work in the first place and sort the problem out before the big freeze this weekend.

 

[JohnD]

get them to fit a room stat as well

not to have one is lunacy (sorry)

 

[Ridgway132]

get them to fit a room stat as well

not to have one is lunacy (sorry)

Interesting, The Corgi installer said the complete opposite and recomended TRV's instead of a room stat due to the size of rooms, citing we would be able to control the temp in each room independantly. So had the room stat removed and TRV's fitted. So who's right?

 

[JohnD]

Me!

you need a room stat
addding TRVs as well is even better

If you have no room stat, then even when the house is hot and all the TRVs are shut, the boiler will be trying to pump hot water round the system because it has not been told to stop.

The room with the room stat needs at least one rad with no TRV

 

[Ridgway132]

Me!

you need a room stat
addding TRVs as well is even better

If you have no room stat, then even when the house is hot and all the TRVs are shut, the boiler will be trying to pump hot water round the system because it has not been told to stop.

The room with the room stat needs at least one rad with no TRV

Thanks John, seems we have been told a whopper! Just had the senior engineer around and guess what - There was a wiring problem in the controller/ junction box. They are going to fit a wireless room stat for free as a way of saying sorry. Have a warm house now! How did I get them here so fast - I have my 80 year old mother living with us - nuff said. Thanks again to all who contributed

 

[urakai]

well done john. good fault finding son!

 

[JamesBeasley]

I have the opposite problem to this but it had worked before and the wiring has not changed.

I get heating just no hot water unless I switch the heating on - which is fine when you consider that it will be on soon.

I have swapped the 2 port valve over for a new one as I thought it was that. It has fixed the thermostat issue with the heating (no way of controlling it before through room stat just always full blast). But when I switch the hot water on only the boiler does not fire?

Programmer / 3 port valve??????

 

[kevplumb]

Programmer / 3 port valve??????

and they are

 

[JamesBeasley]

honeywell st6300a programmer

mid position valve (what I have always know as a 3 port valve)