Heating Advice

[baluachrach]

Hi looking for some advice please.
Our House seems to have a fully pumped system with a mid position valve. 6 Radiators are fed off the CH side with 10mm copper presumably fed from a manifold. The HW side heats the HW Cylinder but also 3 other radiators (15mm pipe's) in an extension to the original house. The problem is that our boiler has burst. Before replacing it are we better to try and move these 3 radiators onto the CH side of the system? Thanks

 

[moggridgeplumbing]

If your having the boiler changed then that would be the time to connect these rads over to the CH side. Can't see the logic in why they where piped to the HW side in the first place.

 

[baluachrach]

Ok cheers. Is there anything actually wrong with a set up like this? The 3 rads all have trv's so can turn them off when just want hot water in the summer time. Just wondering if this could have had anything to do with the boiler failing?

 

[moggridgeplumbing]

Cannot see the bolier failing, but why waste hot water circulating around the 3 radiators, even though they have trv's. Wasted energy and gas. Not done the calculations, it could just mean pence, but not right all the same.

 

[Nige F]

Because there weren`t any spare connections on the manifold

 

[baluachrach]

Hi been having another look at the pipe work and It seems after the pump is the motorised valve and on the HW side the vent is up to the F+E tank before going to the coil. The cold feed is into the return. Is this wrong as I think I have read that the vent and feed should be before the pump?

 

[Mrmethane]

Hello

Sounds like an old y plan system with a twist. Usually the flow from the boiler came directly into a 22mm tee from which the expansion carried on to the f&e tank, the cold feed dropped into another tee a short distance away before the 22mm dropped into the circulating pump and then the three port valve. Thess systems seemed to work well and were reliable in operation. If you pipe it like this you should not go far wrong.

 

[baluachrach]

Mrmethane, Thanks yes the cold feed is close to the expansion but the feed drops into the return to the boiler.
From the boiler I have flow, Pump, MV, (CH side to rads then return to Boiler) HW side (28mm) goes to Tee (expansion and Coil) before the Coil there is another Tee that goes to 3 radiators which then returns into the return from the Coil then the cold feed joins before returning to the boiler - If that lot makes sense??

 

[Mrmethane]

Hello

Yes it does sorta, it may be better you take a little time out during the spring and summer and re-pipe your system in the old y plan way and put all your radiators on the ch side of the 3 port valve. try do a little diagram of how you think it is piped now, and post it.

 

[baluachrach]

MrMethane, sorry for the delay in posting back. I have lifted some floors and managed to trace the existing pipework as best i could.
I have tried to draw out as per attached diagram,

Untitled

• baluachrach
• 27 Mar 2011
• 1

Thanks again

 

[baluachrach]

Hi anybody able to offer some advice on my diagram would be most welcome. Cheers

 

[Steambod]

Hi anybody able to offer some advice on my diagram would be most welcome. Cheers

Recommend shifting the 3 rads onto the rest of the heating system as suggested. Also move feed tank cold feed and vent pipes onto suction side of pump 6" apart. Probably need to put a manual air vent on the flow pipe to vent the rise to the cylinder.
I would also recommend putting a bypass between the pump outlet and the boiler return: using a differential pressure valve will ensure that should your TRVs close the pump won't be running against a dead end and as I expect your new boiler will incorporate pump overrun this would be a good idea.

 

[Agile]

It would be better to convert the system to a sealed one when the new boiler is fitted.

Because wires are cheaper and easier to install than pipes, it will probably be cheaper/easier to fit two new two port valves at the cylinder and the feed to the extension so the extension becomes a second heating zone.

As a matter of interest what make/model of boiler do you have which has "split"?

Tony

 

[ajrobb]

At least be aware of modern W-plan systems. Separate CH and DHW flow temperatures can give you savings on heating bills and faster recovery on DHW.

 

[Eeejit]

if your diagram is correct, where is the expansion taken up when three port valve is on heating only?