Hi. I am new to underfloor heating. I am in a new build. I have two pumps feeding two manifolds connected in parallel and feeding two different ground floor levels. There is a hot/cold mix dial for each so supply hot water is diluted to a lower temperature as I understand. While balancing, I set the first of these to feed 34 degrees centigrade (indicated 36 degrees on its control). I measured this with a thermocouple. The second control is a different make. It is not calibrated in degrees but marked 'hot' and 'cold'. When I set it to full cold 'min', it measures a feed temperature of 56 degrees, way higher than I want. Set to maximum, the feed temperature is around 58 degrees. Any ideas why this second mix control may not be working?
Underfloor Over Temperature
- Thread starter InMyHO
- Start date
Make and model of valve would be helpful. If the head is removable, is it sitting properly on the valve?
Also check whether there is any manual overide on the valve to assist with filling the circuit. This may have been left locked open.
Also check whether there is any manual overide on the valve to assist with filling the circuit. This may have been left locked open.
In case it helps, the calibrated control that is working is branded 'Reliance' (are they called tempering valves?). The uncalibrated control that doesn't work is labelled Inta, which I think stands for Intatec. I would not want to put any blame on the device till I understand the issues though.
Hey Oilhead, we crossed over. Thank you for your reply. I'll try and look for some lever or button that might lock the valve open.
I would imagine you mean the mixing valve or blending valve.
Check the one that's not working properly is piped up the right way.
Check the one that's not working properly is piped up the right way.
Ah, so removing the knob (Philips screw holding the plastic knob and aluminium printed disc), it seems like you can wind the valve further. It's as if the valve has an operational range but you can alter that range by removing the knob, turning the valve spigot and replacing the knob in a different orientation - whether that's intended or not.
Could that be a part of the installation adjustment that was not carried out?
Could that be a part of the installation adjustment that was not carried out?
Will do. At least I can check that the two circuits are the same.
Yes, the term 'blending valve' makes sense to me. That's exactly what it's doing.
That's where I'd start.
Could well be the answer. Those valves are quite common as blending valves on combi's so it may be able to be turned down. You have nothing to lose by trying it. There would be no manual overide on that valve.
It begs the question why the installer did not use the same valve as on the other circuit; penny pinching?
So, checked and yes, one of the connections is marked in red and that's the one where the hot feeds in. So, it does seem to be plumbed the right way around.
I am now checking the extra range of adjustment on the valve to see if that helps.
Will have to wait a while. Obviously, after heating the room a little with the valve as it was, both the supply and return are pretty hot. It'll take a while for the water to cool and for the blender valve to not just be mixing hot water with more hot water 
!
I assume that if this does not solve the issue, then the next step is get a plumber to fit a replacement blender valve.
!I assume that if this does not solve the issue, then the next step is get a plumber to fit a replacement blender valve.
Yes, it is annoying and seemingly unnecessary having two different types of valve. Though I have to say that two valves that work would be the ideal, rather than two that don't. I note that the heating was never set up. Nothing was balanced. Indeed, the installers did not seem to know that it needed to be balanced.
I have one room that's never been below 24 degrees centigrade. It is both on the overly hot manifold and was the smallest room yet set to have the highest flow rate.
OK, so the problem valve, by taking the knob off and adjusting it as far as I can I could get the temperature down to 46, so about 12 degrees above where it needs to be.Will have to wait a while. Obviously, after heating the room a little with the valve as it was, both the supply and return are pretty hot. It'll take a while for the water to cool and for the blender valve to not just be mixing hot water with more hot water
I assume that if this does not solve the issue, then the next step is get a plumber to fit a replacement blender valve.
I guess it could be that the pipe that feeds the return (cold) water is blocked. Can anyone think of anything else that might be causing the issue?
I think some of those Inta blending valves only have a small range. Eg 20-25°C.
It may not go as low as needed.
It may not go as low as needed.