One room won’t heat up

[Newbie1]

I have newly installed UFH. All seems fine, actuators working, heat differential out/return, thermostats call and I see the flow rate/actuator working as it should.

All good except one room (the smallest) it just won’t heat up at all! Room is between 14-18C depending on outside temp. I have set at 27C with no impact on room temp.

 

I have hired a thermal camera to see if anything obvious.

I started with the thermostat low and turned up high, I could see system respond, the hot water working through the system from the manifold and underneath the floor, but many hours later and the floor is still cold and room temp unchanged.

 

I can see on the thermal imaging camera a difference on the pipes in the floor. The UFH pipes are measuring 21C and the gaps between 17C - I have set the thermostat at 27C.

 

Compared to adjacent room (double doors through, same wood flooring) this is sitting at desired temp 23C. Pipes on camera show 27C and gaps between 22/23C.

 

The installer completed a water purge of the system to remove any trapped air with a hose but no change.

 

Any ideas I am at a loss and the installer has given up as all seems to be working electrically/plumbing wise.

 

thank you!

[ProDave]

Do you see water flowing properly on the flow meters on the manifold?

[JohnMo]

When you compare the flow rates of the two rooms what are they?  For the shortest circuit the flow rate should be the lowest.  This will give the more time to transfer the heat from the water to the floor.

[Newbie1]

Hi yes water seems to be flowing properly and I calculated flow rates from length and used those as I thought that might be a problem. The smaller loop (in cold room) I have tried at different flow rates, it’s now set at flow rate of 1.5 at moment. Other larger room at just over 2.

[Temp]

Double check that the stat in that room controls the floor loop in that room. In our case the electrician had swapped two over so the stat in the cold room was actually controling the loop in a different room.  That caused one room to go full hot and the other full cold. We only noticed the cold room. Once I figured it out what was wrong it was easy to swap the valve heads on the manifold. Perhaps you have same?

[Temp]

An air lock is also a possibility.  I think you can still have good flow rates with water flowing faster past the bubble.

[Newbie1]

We tried the rooms separately and checked thermostat to actuator so confident the right thermostat is connected to the right loop. There is one thermostat for this loop and room next door as one thermostat and three loops.

 

 Would an airlock show on the thermal camera? And would it make all of that loop cool?

[ProDave]

If the loop to the cold room is showing flow on it's flow meter then it won't be an air lock.

 

Increase the flow on that loop as high as it will go (watch you don't unscrew the flow meter housing completely)

[Newbie1]

3 hours ago, ProDave said:

If the loop to the cold room is showing flow on it's flow meter then it won't be an air lock.

 

Increase the flow on that loop as high as it will go (watch you don't unscrew the flow meter housing completely)

Hi we have tried that and left it for days with no impact and everything in between too. Will try again though. 

[ProDave]

Do you have the IR camera still?

 

If so I would shut off all flow to all the loops, except the one that appears to be not heating, and then when it has had time to equalise, use the IR camera to see just where the heat from that loop is going to.

[TonyT]

What room is it?

does it have more outside walls than the rest?

 

can you be sure there is enough UFH in the ground as per the drawing at the correct spacing?

[Nickfromwales]

4 hours ago, ProDave said:

If the loop to the cold room is showing flow on it's flow meter then it won't be an air lock.

Not always. The water can crawl along the bottom of the pipe and under trapped air, giving around 75% less cross sectional area of contact from the heated water. The water will still flow in one end and out the other and register on the flow gauge.  

 

 

Edited December 8, 2021 by Nickfromwales

[Nickfromwales]

34 minutes ago, ProDave said:

if so I would shut off all flow to all the loops, except the one that appears to be not heating

Deffo the next thing to do. Shut off the flow to everything else except the cold room and report back after 12 / 24 hours.

[Onoff]

Turn the pump up to 11? ?

[Newbie1]

1 hour ago, TonyT said:

What room is it?

does it have more outside walls than the rest?

 

can you be sure there is enough UFH in the ground as per the drawing at the correct spacing?

It is the downstairs toilet, hall and entrance. It is laid as to design plan ad per supplier and is a 48 metre Loop. Thermal camera shows that there isn’t any heat transferring to surrounding floor and the loop itself doesn’t reach even target room temp. I spoke to Hetta and they say it should work - there is no heat transfer coming though at all so can’t be room size/loop size.

[Newbie1]

1 hour ago, Nickfromwales said:

Not always. The water can crawl along the bottom of the pipe and under trapped air, giving around 75% less cross sectional area of contact from the heated water. The water will still flow in one end and out the other and register on the flow gauge.  

 

 

Anyone know how this might look on thermal camera other than low heat transfer (which I see). The installer has refilled and bled and is adamant that done correctly so there should be no air in there.

[Newbie1]

1 hour ago, Nickfromwales said:

Deffo the next thing to do. Shut off the flow to everything else except the cold room and report back after 12 / 24 hours.

I have tried this and made no difference but not tried with thermal camera. Will try again and report back!

[Newbie1]

Hi update - turn off heating to all loops except for the room that won’t heat up. Used thermal camera and found that the out and return of this loop go through the open lounge area. Surprising loops show good heat and transfer to adjacent area 30C and in between loops 24C. Once the loop crosses the threshold to hallway temperature of loop drops to 22C in some parts and adjacent area 17C as follow round and cross threshold back into lounge temp recovers to 30C. Suggests that they have fitted differently in this room/not used same substrate. Any other thoughts?

[ProDave]

2 minutes ago, Newbie1 said:

Once the loop crosses the threshold to hallway temperature of loop drops to 22C in some parts and adjacent area 17C as follow round and cross threshold back into lounge temp recovers to 30C. Suggests that they have fitted differently in this room/not used same substrate. Any other thoughts?

So the cold room is an extension (either original or added on)

 

It is starting to sound like they "forgot" to put any insulation under that floor and most of the heat is going down to heat the earth under the house?

 

Is this a new house? old house? Who did what in terms of insulation and laying pipes etc?

 

[Newbie1]

1 hour ago, ProDave said:

So the cold room is an extension (either original or added on)

 

It is starting to sound like they "forgot" to put any insulation under that floor and most of the heat is going down to heat the earth under the house?

 

Is this a new house? old house? Who did what in terms of insulation and laying pipes etc?

 

It’s not an extension it’s l990’s house with internal garage. The cold room is the front entryway with stairway and toilet and double doors through to lounge. We had full refurbishment to make open plan and install of UFH throughout all ground floor. We have engineered wood floor throughout all ground floor. So same builder and team for install throughout. But yes I think you are right they have not used insulation at the front of the house and heat is just going down. It’s certainly not transferring heat up to wood floor.

Edited December 8, 2021 by Newbie1

[ProDave]

Do you have any photographs of the work in progress to compare the good and bad areas?

[Newbie1]

5 hours ago, ProDave said:

Do you have any photographs of the work in progress to compare the good and bad areas?

Unfortunately no. We had to move out for the refurb and only periodically saw the property. For loops that work fine I recall seeing some WIP with insulation (looked like white polystyrene with loops laid into the inset) but don’t recall this room. So fear we will have to list up the flooring. Installer is no longer responsive.

[ProDave]

6 hours ago, Newbie1 said:

. Installer is no longer responsive.

Isn't that always the way when things go wrong.

[scottishjohn]

is the floor any different construction than the rest of the house -is this a new build with total concrete slab in all rooms  of are pipes fixed to under side of the flooring 

 

Edited December 10, 2021 by scottishjohn

[Temp]

If there is no air lock, flow rates are ok and flow and return temperature are similar to other rooms then I think it can only be an issue with the installation.

 

Is the return temperature similar to other loops? Higher? Lower?