Adding UFH circuit to Potterton Performa 28 combi

[coatesuk]

Advice needed please!

I have recently added UFH to my lounge & conservatory (retro-fit overlay) which is brilliant. It has its own room stat but is being run totally independantly of the primary heating programmer as neither I, nor my plumber, knew if it was possible to link it into the existing programmer. So I have a plug-in timer running the UFH pump, set to come on 5 mins after and switch off 5 mins before the primary timer. Anyone have any ideas on how I could link the 2 systems together so that I can run both off the same programmer?

Potterton Perrforma 28 Combi boiler (in garage)
Rad heating thermostat & programmer: Remote wired programmer & thermostat (in hallway)
UFH heating thermostat & programmer: Remote wired thermostat (in lounge); plug-in programmer "switch" plugged into standard socket close to pump!

Any help greatly appreciated.

 

[ChrisR]

Use 2x 2 port valves and wire it up essentially like a S plan system.
http://content.honeywell.com/uk/homes/Catalogue/Sundial Plans/3.2 S Plan.pdf

Works fine, though check the need for a bypass in the boiler instructions.

 

[coatesuk]

Use 2x 2 port valves and wire it up essentially like a S plan system.
http://content.honeywell.com/uk/homes/Catalogue/Sundial Plans/3.2 S Plan.pdf

Works fine, though check the need for a bypass in the boiler instructions.

ChrisR, thanks for the reply. Do I need that if all I'm trying to achieve is to get the UFH pump switching on/off at the same time as the boiler?

 

[gazthepottertonengineer]

i would definately fit an external pump as well as the resistance on the ufh is big

 

[Agile]

If its installed as a conventional UFH then it will have a circulating pump and blending valve set at about 50*C for the UFH.

If its been connected as if it is a rad and sent heating water at 80*C then you may be risking thermal damage to the floor!

Tony

 

[coatesuk]

The system is a conventional UFH system i.e. it has it's own pump, mixing valve, vents, manifold etc. and is run at approx 50 degrees. The only thing different is this is overlay - i.e. it's not cemented in - it's in panels under the floor.

My problem is simply the timer and power to the pump. Everything works as a conventional UFH and heating system except I'm stuck as to how I could wire in the pump and stat for the UFH to the combi boiler so that the normal heating and the UFH share the same timer, instead of having a seperate timer for the UFH which is set to the same times as the boiler timer.

 

[bab]

why do want to link them if it works ok.

 

[coatesuk]

why do want to link them if it works ok.

I would like them both running off the same timer. Boiler & UFH manifold, pump etc. in garage, as is plug-in timer for UFH. Programmer for boiler in hallway. Therefore, if I choose to extend the boiler timer by 1 hour for an evening (normally have heating off at night), I have to go out to garage to change UFH timer too, if I want it to run for 1 hour longer too. If I have it all running off the same programmer/timer, I don't have to worry about UFH trying to pump when the boiler's not on, and know that when primary heating is on, so is UFH.

 

[ChrisR]

Just connect the "calls" in parallel and you'll bring the boiler on when either the rads or the UFH need heat. No problem there. The timer is controlling the boiler CH in the normal way.

But then the pump in the boiler will pump water off to the UFH whenever the rads are on, and the UFH may pump water round the rads, which is why you need the zone valves.

Wth 2 zone valves you can have separate timers, or a single programmer with 2 channels, and do it properly! You'll probably need a programmer with volt free connections, like a Danfoss FP975.

 

[coatesuk]

Thanks for the help ChrisR.