UFH not working, Return valves stay cold as compared to heat valve at Manifold and rooms always never reach 16 or above degree heat

[junaid]

Hello Experts,

 

My name is Junaid , I am looking for some advices what to do as the next step for my UFH, I am expat from Germany with little German speaking proficiency and having trouble to find the right solution for my house! There is always miscommunication, lies,  etc. by the heating company and plumbers so I decided to do now many things with my own hand and using Youtube expert opinions.

The house is from build year 1965 its a detached house with not too much insulation, 158sqm of house and all windows are double glazed so I know some of the heating loss is possible.

The manifold have the issue that its return valve have been completely cold like 19°c-25° but hot water lines are between 44°c-50°c (I set the flow higher to observe the measurement), I have drained all the manifold lines from the rooms one by one by using a hosepipe and connecting it to the tap connection and removed the air that was stuck in between..

 

issues that still have not fixed and I really need help so the rooms can be warmed. at the moment its -5°c outside and our rooms are 12° or 16°.
Return water is always cold as I mentioned earlier, when i speak with the installation guys they said there is problem with your manifold not our system( Bosch gc5800iw),

 

also some of the people said that we have used the wrong pipes but as per the details I do not see this is the issue. I am 100% sure when the return valve start working and from one side the heating water will push water and exit with a little difference from the return valve the rooms will get warmer.

 

One more tip/Observation from the recent visit by the installation guys I closed all the two floors main lines and only opened 2 rooms circles from the manifold so that only these 2 rooms gets the heating water to see if the manifold setting can be choose instead of 0.5L/m  to other more higher and realized that the pump from Bosch is not so powerful that I can reach 2.5 or 2L/m setting on the manifold. I was unable to reach the higher setting I dnt know the reasons but many videos I saw its easier to set 2L/m (mine never go above 1) finally with the last experiment I reached 1.5L/m value. 

Do I need another Pump between the Bosche connection before the main water lines( rücklauf und vorlauf hauptleitung)

 

please let me know your questions , I look forward for the positive feedback from the community.

 

 

 

 

[Andehh]

What's underneath the floor? How much insulation?

 

If you are only able to achieve 0.5l/min flow rate with the pump then that's an issue in my mind. I would expect to see a pump per manifold there if your loops are anything other then incredibly short... But I'm not an expert!

 

 

Your boiler has water out at 39 degrees, but returning at 38 degrees?

 

[MikeSharp01]

12 hours ago, junaid said:

I have drained all the manifold lines from the rooms one by one by using a hosepipe and connecting it to the tap connection and removed the air that was stuck in between..

Hi Junaid and welcome to the forum for people like us. 

A couple of questions:

 

1. When you did the hose pipe connection did you get good flow through all the lines?

2. It looks like you have two manifolds, is that right, and if so how are they connected together.

3. Is the pump a separate unit or built into the boiler? If separate can we have a picture and the makers plate to show what sort of a pump it is?

[MikeSharp01]

Just had another look at your photos. The boiler image is showing 39 deg flow (out) and 38 deg return (back in) on the heating circuit. Is this this a true set of numbers because if it is it suggests some sort of bypass so water has found a way back to the boiler without going round the heating loops. Maybe an open valve somewhere?

[Conor]

Lots of poss factors here. Let's break it down.

 

What was the overall design in terms of heat loss / flow rate? Who did this design?

 

What length is each loop and what is the designed flow rate?

 

As a rough guide, you should be seeing something like 2l/pm for each large loop, and 0.5-1l/pm for small rooms like bathrooms.

 

It appears that the UFH pipes have been laid directly on the original, uninsulated concrete floor? What's the est of the floor buildup?

 

At a guess what is happening here is insufficient flow rate through the loops due to no dedicated manifold pumps, plus you are heating a (assumed) uninsulated concrete slab. Even if you get flow rates sorted, it'll struggle to be warm or efficient as a significant amount of heat energy will be going in to the ground.

 

[junaid]

On 30/12/2024 at 08:31, MikeSharp01 said:

Hi Junaid and welcome to the forum for people like us. 

A couple of questions:

 

1. When you did the hose pipe connection did you get good flow through all the lines?

2. It looks like you have two manifolds, is that right, and if so how are they connected together.

3. Is the pump a separate unit or built into the boiler? If separate can we have a picture and the makers plate to show what sort of a pump it is?

hello Mike, 

thanks for the feedback.

1. yes I received a good flow, as this was my first time knowing the system I learned that as fast I make the flow from tap water the value on the manifold 0.5, 1m/l etc increases so I learned from this experiment why my flow cannot be adjusted to higher value when I am connected to the boiler, (I think the pressure from boiler system is not much)

2. I have 3 manifolds in total on every floor. the difference is that ground floor has 5 circuits, 1st floor has 6 circuits, and top floor is 4 circuits.

3. No there is no additional pump that is why I have attached my delivery receipts where an addition pump was delivered but not installed 

the pump picture is from my Bosch system unit

 

4. also your last question: the picture temperature is not true I am not sure how this is sensing 38 and 39 ° flow but this value is False 

[junaid]

On 30/12/2024 at 07:49, Andehh said:

What's underneath the floor? How much insulation?

 

If you are only able to achieve 0.5l/min flow rate with the pump then that's an issue in my mind. I would expect to see a pump per manifold there if your loops are anything other then incredibly short... But I'm not an expert!

 

 

Your boiler has water out at 39 degrees, but returning at 38 degrees?

 

its the old house insulation we have not removed the complete floor to save the cost, since we milling was done on floor the pipes are layed directly on the older insulation.
I tried to close all the circuits and only ran 2 of my rooms so technically the warm water runs through only 2 loops rights which should easy for hot water to enter and return but it also didnt returned hot water. 5°loss of temp  i can expect but there is now almost 20°difference in hot and warm valves

[junaid]

On 30/12/2024 at 08:45, Conor said:

Lots of poss factors here. Let's break it down.

 

What was the overall design in terms of heat loss / flow rate? Who did this design?

 

What length is each loop and what is the designed flow rate?

 

As a rough guide, you should be seeing something like 2l/pm for each large loop, and 0.5-1l/pm for small rooms like bathrooms.

 

It appears that the UFH pipes have been laid directly on the original, uninsulated concrete floor? What's the est of the floor buildup?

 

At a guess what is happening here is insufficient flow rate through the loops due to no dedicated manifold pumps, plus you are heating a (assumed) uninsulated concrete slab. Even if you get flow rates sorted, it'll struggle to be warm or efficient as a significant amount of heat energy will be going in to the ground.

 

Thanks for the feedback, could I directly jump to one of the topic you mentioned, can we have a pump with the manifold even tough from my storage room the boiler is pushing the warm water in the main lines? the installation guy told me that and additional pump is ONLY installed when there is a storage tank in between. he said that the boiler is pushing enough pressure that your return flow works but I am not satisfied what I am seeing in my house experimenting things.

[junaid]

So I feel a little stupid to mention this but believe me or not I just have observed that If I remove the cover of my Bosch boiler system it start to push warm water until 52degrees and as soon as I put back the cover it starts to drop the value and stays between 29-30 degrees.

Is there any expert who may know if the system needs some kind of earth connection etc.? becasue this seems to be a very stupid statement from my side but please don't laugh about it.

 

[ProDave]

Is that a type of boiler where the front case forms the air seal for the inlet air? (and you should not run it without the cover on)

 

If so is there a blockage on the outer part of the flue that draws the air in?  Works with cover off (drawing air from room) starved of air with cover on?

[MikeSharp01]

13 hours ago, junaid said:

I have 3 manifolds in total on every floor. the difference is that ground floor has 5 circuits, 1st floor has 6 circuits, and top floor is 4 circuits.

Sounds a lot for a 68W pump, has to overcome the head issues and then deliver flow.  I would isolate all but the ground floor (assuming the boiler is on the ground floor) and see if you can get a decent heating system out of that single manifold I think that might give you an idea of the scale of the problem at least. Others will have other ideas I am sure but that would be my starting point.

[junaid]

On 01/01/2025 at 20:28, ProDave said:

Is that a type of boiler where the front case forms the air seal for the inlet air? (and you should not run it without the cover on)

 

If so is there a blockage on the outer part of the flue that draws the air in?  Works with cover off (drawing air from room) starved of air with cover on?

Hello ProDave, Thanks for the feedback, today I looked about your suggestion and used a thin foil to seal the front panel and realized that somehow the boiler needs air intake which was blocking. also On top on the boiler there are 2 Inlets labeled as CO2 and O2. (as I have shared the picture) I opened the O2 inlet and then closed the front cover of my boiler so it started to work as usual and I do not have remove the front cover anymore. now the second part is still that my return valves are almost 20 degree different which is still a mystery for me.