Help with wet UFCH please ?

[Upamountain]

Help needed with our UFCH - half our house is cold!


A year ago we moved into a barn conversion that was completed around 2012. It’s a long low stone building built into a Welsh hillside with only one room upstairs that’s heated by 2 conventional radiators. The whole ground floor is heated by an Uponor wet UFCH system. The end of the house nearest the boiler is served by one manifold which seems to be running fine - it serves seven areas, the manifold inflow temp is 30 and outflow 18 and the rooms are a comfortable 19 degrees.


However the other, slightly lower, far end of the house (including the upstairs room) we can’t get warmer than about 15 degrees. It’s served by a second manifold with five circuits running off it. The problem seems to be that the water going into the manifold is not hot (inflow temp around 24, outflow around 22 degrees).


We noticed that end of the house was slow to heat last winter but not as bad as now. The actuators are all radio controlled from room thermostats and seem to be functioning. The flow meters all appear to show flows of about 2 when that circuit is active (they are cloudy and difficult to read so I’m guessing the circuits need flushing but doubt that’s the whole problem?


We’ve tried turning down all the thermostats in the “working” end of the house to divert HW but this hasn’t helped. The pumps seem to be working ok.


Sorry about the non-technical description. Any advice gratefully received as we haven’t been able to find an UFCH engineer locally And the children are due home for Christmas!

 

[Johntheo5]

Help needed with our UFCH - half our house is cold!


A year ago we moved into a barn conversion that was completed around 2012. It’s a long low stone building built into a Welsh hillside with only one room upstairs that’s heated by 2 conventional radiators. The whole ground floor is heated by an Uponor wet UFCH system. The end of the house nearest the boiler is served by one manifold which seems to be running fine - it serves seven areas, the manifold inflow temp is 30 and outflow 18 and the rooms are a comfortable 19 degrees.

That seems a very high dT, 22C, especially with a return temp of 18C, you might expect the return to be at least a few degrees above the room temperature of 19C, however, your not worried as the room is being heated to your satisfaction with a UFH output of ~ 21.5kw (a very high output) assuming a flowrate of 2.0LPM/loop,

However the other, slightly lower, far end of the house (including the upstairs room) we can’t get warmer than about 15 degrees. It’s served by a second manifold with five circuits running off it. The problem seems to be that the water going into the manifold is not hot (inflow temp around 24, outflow around 22 degrees).

Can you raise the TMV (mixing valve) setting to say 35C?, what is the boiler flow temperature.
At that flow rate of 2.0LPM, below, and a dT of 2C, (24-22) that UFH output is only 1.4kw, not a lot.

We noticed that end of the house was slow to heat last winter but not as bad as now. The actuators are all radio controlled from room thermostats and seem to be functioning. The flow meters all appear to show flows of about 2 when that circuit is active (they are cloudy and difficult to read so I’m guessing the circuits need flushing but doubt that’s the whole problem?

 

[Upamountain]

Thanks for your reply. I think the first high dT you mention may have been due to that manifold having very little flow due to us turning down its thermostats in the hope of sending more hot water to the manifold that’s too cool. With all the room stats now set at 20 pipe temps are now - Upper 25.5 and 22: lower 26 and 22.5.
I haven’t changed anything else. I‘ll see what the room temperatures are tomorrow- still around 15 at present unfortunately.

 

[Johntheo5]

THe manifold flow temperature is determined by the TMV setting so once the boiler flow temperature is greater than say 50/55C then there is no reason IMO why you can't set the manifolf flowtemp to 30/35C irrespective of whether the other roomstat is calling fof heat or not, its possible that the TMV flow & return pipes have been installed incorrectly or the TMV isn't working properly.

 

[snb1]

the reason that the flow and return temps are so large is either due the system being only on for an hour or 2 or the flow loops are over 100m and then the flow rates would need to be increased.

If you can post some pics of both manifolds showing the pumps etc and blending valves along with the boiler settings we would have a better chance of working out what could wrong.

My first instinct is that the second colder manifold is further away from the boiler ( boiler main pump is not strong enough or pipework too small and the first manifold is taking most of the heat) pictures and a rough sketch with distances will help

 

[Upamountain]

Thanks for your replies. I’ve had both circuits running for a few days now for things to stabilise before updating this thread. I‘ve also been monitoring the temp’s of inlet and outlet of both manifolds to get a better idea of what’s going on. Another thing - the UFH used to run of an oil fired range which was replaced with a Vaillant ASHP system by the previous owners 2 years ago.
So - temperature of inlet water into both manifolds seems to have stabilised at around 28. Likewise outflow at around 25. Most of the house is now at 18-19 degrees which suits us.
Remaining problems -
All the flow glasses remain really murky - flow indicators only just visible.
The far ground floor bedroom downstairs remains stubbornly cool at around 16 degrees.
The single upstairs bedroom served by 2 radiators is the same - no discernible warmth from them.
May not be relevant but last winter the ASHP seemed to cost a fortune to run.
Happy to post pics if helpful - just tell me what of (I’m on a very steep learning curve here!)

 

[Johntheo5]

The UFH might still have TMVs + a manifold pump still installed which may be required with a HP, if so see, what settings the TMVs are set to or post a picture of them + manifolds.

 

[snb1]

you said it was connected to a boiler, now it turns out it's a heat pump. Make sure you leave it switched on for heating 24/7 at static temps for each room. When it gets slightly colder these heat pumps produce a lot less heat when you need more heat!

 

[Upamountain]

you said it was connected to a boiler, now it turns out it's a heat pump. Make sure you leave it switched on for heating 24/7 at static temps for each room.

Sorry to mislead - I accidentally typed “boiler end of the house” in my original post (cause that’s where it used to be) - I should have been more clear.
And yes, all heating settings,thermostats, rooms have been static for the past few days now. I will try and post pictures of the two manifolds - unfortunately the one at the ASHP end of the house is virtually obscured by kitchen units.

 

[Upamountain]

So…photo overload - the 1st shows the mixer valve (?) next to the manifold in the upper part of the house. This seems to opened and closed fairly frequently (the noise is quite noticeable).
2nd shows the manual for the unit above that manifold visible in picture 4.
Pic 5 shows the pump next to the 2nd manifold at the other end of the house as shown in the last pic.
You can see the little Amazon thermometers I’ve been using to get a rough idea of the pipe temperatures.
Sometimes the inlet temp on the 1st manifold jumps to just over 30 degrees (due to the mix valve functioning?)
but mostly the in out temp diff is still about 2-3 degree. With slightly warmer weather today the temp in the cold far bedroom has crept up to 17 but in the upstairs bedroom there is still no heat coming through to the rads.
Thanks again in advance for any advice.

 

[snb1]

on the last picture it shows that bedroom 2 actuator is off (closed ) and bedroom 1 righthand actuator is off (closed). what speed is the pump set to in picture 4? needs to be on max speed (3).

Need a clearer picture of the first manifold to see which actuators are open.

On the second manifold unless bedroom 1 had just reached temp or has only just turned on then it looks like either a faulty actuator or wire has come loose

 

[Johntheo5]

So…photo overload - the 1st shows the mixer valve (?) next to the manifold in the upper part of the house. This seems to opened and closed fairly frequently (the noise is quite noticeable).
2nd shows the manual for the unit above that manifold visible in picture 4.
Pic 5 shows the pump next to the 2nd manifold at the other end of the house as shown in the last pic.
You can see the little Amazon thermometers I’ve been using to get a rough idea of the pipe temperatures.
Sometimes the inlet temp on the 1st manifold jumps to just over 30 degrees (due to the mix valve functioning?)
but mostly the in out temp diff is still about 2-3 degree. With slightly warmer weather today the temp in the cold far bedroom has crept up to 17 but in the upstairs bedroom there is still no heat coming through to the rads.
Thanks again in advance for any advice

Can you measure the pipe with the hottest temperature (the HP flow temperature) on that what looks like a electronic mixing valve, is this feeding all the manifolds or just one?.
It shouldn't be moving around frequently, it should give a steady required mixing temperature, whatever that is?, 30C.
On the problem 5 loop manifold you are only getting a dT of say 2.5C, at a assumed flowrate of 2LPM then each loop is only producing 350watts say a total of 1.75kw yet the 7 loop manifold is running at a dT of 12C giving ~ 2100watts/loop.
You should be able to switch off the power to that mixing valve and just set it to give say a fairly constant 35C mixing temp and see what effect this has.

 

[snb1]

Don’t worry about the mixing valve. Whatever the temp
Is set
On the Uponor mixing valve setup the default is expecting a flow temp of around 70 and the HP isn’t going to give that. The mixing valve also shows that it is on max meaning that it isn’t mixing the temp down. My current guess is the Heat pump flow set point maybe quite low. We really need to know which heat pump model. What is the power of it? Send a pic of data badge on the side the heat pump.
Also need to see which controller is used by the heat pump. And also the heat loss calcs or some house dimensions.
Also need the hot water cylinder size and what timings if any that has for hot water control.

 

[Johntheo5]

Don’t worry about the mixing valve.

It shouldn't be operating like this though?
"the 1st shows the mixer valve (?) next to the manifold in the upper part of the house. This seems to opened and closed fairly frequently (the noise is quite noticeable)."

 

[snb1]

It shouldn't be operating like this though?
"the 1st shows the mixer valve (?) next to the manifold in the upper part of the house. This seems to opened and closed fairly frequently (the noise is quite noticeable)."

these mixer valves will continually alter the mixing to create a fixed output temp. But unless the OP is certain that it is this making the noise and its's not the 2 port motor we can't be certain. It could be a broken mixer valve but i doubt it.
I'm fairly certain the setup is causing the heat pump to go into defrost cycle or swapping to hot water too often combined with a reduced output at colder temps affecting it's output.
Perhaps when we see the info come back we can make some definitve suggestions etc