# Mixing Radiators with Underfloor heating problems!



## griff212 (13 Sep 2012)

Hi 

I put in a few years back a large extension ( nearly full size that doesnt require planning permission) I put in underfloor heating in the room as was told this would be better. It was connected to my orginal house heating system.
But its worked on and off and now when I leave on the heating to the room the pilot will switch off on the boiler. If I leave on in the house it is OK but the other room is frezzing . we didnt even use it for the past two winters. Im determined to use it this winter.
details are 

Three bed terraced: 7 radiators, one in each room, 
extension : on underfloor heating connected in main house

the boiler is a vokera mynute 14e
There are two addtional pumps Grunfos , one for main house, one for underfloor.


Can someone point me whats going on . is it time to get a new powerful boiler or is it something else?

Lee


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## hastalavista (13 Sep 2012)

I dont know what u mean when u say the pilot light goes out but UFH works at a much lower temp than the rads so unless the water temp into the UFH loop is reduced then the very hot water from the boiler will just lash through the UFH loops and come back to boiler with little temp drop so boiler will cut out. Try reducing the temp on the boiler to say 30 degrees  for UHF only and see what happens. A more powerful boiler ids not the answer


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## john martin (13 Sep 2012)

Not sure what the underfloor solution is but the Vokera Mynute14 can be a very troblesome boiler.


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## griff212 (14 Sep 2012)

The pilot light meaning the gas ignition in the boiler. When I switch the water to the ufh it goes for about 10 mins then switches off for some reason. When I switch it to the house heating the ignition light stays on no problem. Is there any manual that can show me how to use the ufh. The boiler works no problem on the house... Just when I try and use the ufh it switches off...
Thanks


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## Shane007 (14 Sep 2012)

It sounds like the pumps are working against each other. The 14e has a built in pump also. Turn on the gas boiler, then turn in the UFH. Watch the pressure gauge in the boiler and see if this alters. If so the pumps are creating a negative pressure within the boiler and the boiler is shutting itself down to protect itself.


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## Perry525 (19 Sep 2012)

I set up a similar system some 12 years ago.
It has two self contained loops one hot the other return to the boiler, all the zones were feed from these loops.
It has a tank thermostat controlling a motorized valve.
Three room stats and motorized valves controlling three zones.
Another zone, with underfloor heating controlled by its own thermostat, motorized valve and pump, all this works perfectly.
The take off for the UFH is at 80C the pex pipe inside 4 inch thick reinforced concrete slab covered with ceramic tiles. This keeps our conservatory with floor to ceiling double glazed windows and poly roof at 22C on the coldest winter days and nights.

The only problem is when the sun came out and the temperature hits 50C.

How do you control your set up?


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