Underfloor heating not working

[Mike Burton]

I have underfloor heating downstairs and radiators upstairs. The radiators are working fine, but the underfloor heating has stopped heating up. The pump appears to be fine and the electrics and thermostats seem fine also. There are five zones with four controls (two zones are controlled by one thermostat). I cannot work out where the problem is. I have attached a picture of the manifold setup for the underfloor heating - flow is at the bottom and return at the top. The flow pipe gets hot up to the first two port manifold going from right to left. After that it only gets warm. I would appreciate any help or advice given.

 

[khill]

Mike the zone valve after the pump maybe faulty is it possible to remove
the top and operate it manually?

 

[SimonJohns]

on the bottem manifold there is flow gauges, are these moving or are they at 0?

 

[SimonJohns]

and if the pump is deffo running, remove an actuator head and see if the pipes get hot

from the picture the actuators look closed

 

[Mike Burton]

on the bottem manifold there is flow gauges, are these moving or are they at 0?

The flow gauges are all working.

 

[Mike Burton]

and if the pump is deffo running, remove an actuator head and see if the pipes get hot

from the picture the actuators look closed

I have removed all of the actuator heads in turn and it makes no difference.

 

[Mike Burton]

I have removed the top of the actuator and I can operate it manually, but the valve is open, so this doesn't appear to be the problem.

 

[SimonJohns]

ok

please claifiy

1. boiler is supplying heat
2. There is a flow on flow gauges
3, there is heat going to manifold
4, you have removed the black thermostaic valve to check operation?

we may fix it tonight

 

[Mike Burton]

Yes to 1,2 and 3.
I haven't removed the black thermostatic valve. Is it just a case of unscrewing it?

 

[SimonJohns]

looks to me like it will unscrew, but only the bottem not the whole head

 

[SimonJohns]

im re-reading all of this, and everything seems fine

you have flow
you have heat

it will just take a while to heat up
leave the system on for a couple of days and you should be good

 

[Mike Burton]

Ok, I have removed it and it seems to operate as you would expect.

 

[Mike Burton]

I have had this system a number of years and it is not behaving how it should, so there is definitely something amiss. No serious heat seems to get past the first two port manifold from right to left.

 

[SimonJohns]

thats how it works to regulate the temp of the underfloor

return on bottem, so hot comes from flow,
goes past first return loop
gets cooled/mixed
next loop, even cooler
etc

until floor is warmer and it maintains a nice warm temp, leave it for a few days,

There is a possibilty of a low flow rate of Heating water to the manifold but i wouldnt know this without professional invetigation

And thats the end of simon's 13/12/12 free advice

 

[Mike Burton]

Ok, thanks for your help.