Wet underfloor heating problem HELP!

[Kohini]

Hi... I am looking for advice as to why my we underfloor heating in our extension isnt working. Weve had it 3 years now and it stopped working about 2 days ago. Sorry im not familiar with all the terminology but will provide as much details as i can

Valiant boiler (also 3 years old)
Drayton Tempest Seven Zone controller - 2 zones (normal CH and UFH)
Drayton Combi-stat (controls UFH temp)
Honeywell V4043H1056 valves x2

The main central heating and hot water is ok.

Checks done so far:
1. Boiler pressure was a bit low but still ok, have increased slightly
2. turning on UFH i can hear the boiler running
3. Both honeywell valves set to Auto. Unable to set to Manual as seems like some metal blocking it.
4. Electric is ok to Drayton zone controller
5. There is a thermostatic valve below the boiler, i think its a manifold?? Which looks like a junction pipe close to the pump... Its set to highest 50 degrees.
6. I can hear the pump working and have tried the 3 different speed settings.
7. The red valves beneath the honeywell valves are open.
8. Opened up the Drayton Combi-stat, wiring is in place (3 wires)
9. Tracing the UFH Honeywell valves down to the manifold/pump appeared to be hot and cold intermittently. Also i am sure the turning on of the UFH calls to the boiler, can feel heat in the pipes...

Will try and post some pics... In the meantime if anyone has any ideas on what i can try next would appreciate it..

Thanks

 

[maks_rt_011]

If boiler working ok, and you having heating everywhere except problem area it means that you have a problem with zone valve which responsible for letting hot water on demand . now you got to find out if it is mechanical problem or electrical(controller or thermostat)

 

[erj]

could be the zove valve not opening, I had one last year where the u/f mixing valve had gone fitted new one fine after that. on the u/f heating manifold are the pipes get warm at all or are the flow indecators moving

 

[Kohini]

Thanks for the responses..

Just need some clarification on what these zone valves look like?

The setup is as follows:

Boiler-->honeywell ufh valve (has electrical wire attached)--> red manual valve cut off valve-->manifold/pump

(well i thinks its a manifold according to google images.. Terminates 4 pipes and has a thermostat valve on top)

I think this zone valve must be the honeywell ufc valve, a small metal box... With a mini lever set to 'auto'. I dont see any flow indica tors on them though....

Looks like this

[DLMURL="http://uk.rs-online.com/web/p/products/2463251/;jsessionid=0083AEB1B91246422FF8B418BA18FDB3.226?cm_mmc=UK-PPC-0411-_-google-_-3_MRO_MPN+Oct+2011-_-v4043h1056_Phrase"]Buy Motorised Valves Honeywell motorised valve,22mm comp 240V Honeywell V4043H1056 online from RS for next day delivery.[/DLMURL]

I do feel heat in the pipes from the honeywell ufc valve to manifold.... Although cant feel any heat today... But was definitely hot yesterday.

So this must mean the ufc zone valve is ok?

 

[Kohini]

Ok have done some more diagnostics....

I am sure the ufh zone valve is ok.... Hot water passes this point. It also reaches the downstream manifold which has an inlet and outlet feed for the ufh heating pipes. The inlet pipe and manifold are cold (understandably) however the manifold outlet to the ufh is warm... But the directly connected platic outlet pipe is cold.
I have also checked the drayton room stat, very basic thing.. On/off switch, i checked the contact with electrical screwdriver and it lights up ok..

So i can only envisage it being a blockage of some kind. I am sure central heating and ufh are on seperate feeds from the boiler... So the iron deposits from traditional radiators wont infiltrate into the rubber hosed ufh heating... (or am i wrong??experts pls correct me if so..). And i dont think it has frozen because it failed on thursday when temperature was still around 8 degrees... It was friday when temperature hit zero degrees....

For now have electric oil heater in the room so hope it wont freeze over... Not sure i can think of anything else because the oulet pipe is only 30cm long before it disappears into the floor....

Any more ideas?

Thanks...

 

[erj]

yes your link does show a zone valve, move the lever on the side, if it moves no problem the valve is open, if you feel you are shoving against some thing and as soon as you let go of the lever it springs back it is not opening.
Is the pump on the manifold working OK?,
If after this still not working keep coming back to the mixing valve. good luck

 

[Kohini]

Hi all... Thanks for your help.. Turns out it was the ufh zone valve...