@webcmg 

The schematic on page 24 is the closest I could find with your system, the difference is you have a buffer tank instead of a 40 litre decoupler but they do similar jobs.

The system design is not straight forward and I would strongly recommend working your way through the components to understand the potential impact of each. I’ve also had issues with laser thermometers on pipes so would recommend some clip on pipe dial pipe thermometers from a plumbers merchant. 

Record the temps in order:

1. Hex module (box on wall) right side red and blue are the feed from the heat pump and return. This is the closest to the heating source and will give you a means of comparison to the Vr10 temp probe which is in the top of the buffer tank and should be readable from the VR700 under the configuration screen assuming you have the installer codes. 

There are a number of adjustable points in this system, hex module pump, radiator pump, ufh pump, not to mention just balancing the radiators. This added with the fact it looks like you have bypass valves on both the flow to the radiators and the ufh (which could be passing flow in to the return).

All these points can be adjusted but consistently measuring the temps from around the system you will be able to locate if it is system setup or design. 

Posted by: @webcmg

Posted by: @derek-m

@webcmg 

Hi,

It would appear that your buffer tank has 2 input pipes and 4 output pipes, which is now making more sense. So what temperatures are you getting on the various pipes?

I don't have equipment to measure the temperature accurately (plumber did the last readings), but with an infrared laser thermometer I'm getting

UFH

• 20.3 flow
• 18 return

Radiators

• 21.4 flow
• 19 return

Flow temp on the programmer at the time was 33, target was also 33.

 

Hi,

I can't remember if you said yours is a newly installed system that has never performed correctly?

I have been working for while with a lady experiencing similar problems to yourself, and after numerous tests I'm coming to the conclusion that the main problem is associated with the water flow around the buffer tank.

If the water flow around the buffer tank is correct, then the temperature of the water flowing out of the buffer tank to your radiators and UFH, should be approximately the same temperature as the water flowing into the buffer tank from the ASHP. In the same manner, the return water from the buffer tank to the ASHP, should be at approximately the same temperature as the return water from the radiators and UFH going into the buffer tank. When the system is functioning correctly there should be a delta T of approximately 5C between flow and return temperatures.

As an example, if the water flow temperature coming from the heat pump is 35C, then the water going to the radiators and UFH should be approximately the same. The return water coming from the radiators and UFH should be in the region of 30C, as should the temperature of the return water to the heat pump. Any large differences would probably be caused by mixing within the buffer tank, which of course will affected the operation and efficiency of your system.

You could try measuring the temperature of the pipework around your system by using your IR temperature gun, but if you do not get meaningful results then purchasing one or two cheap temperature meters may be worthwhile.

Posted by: @webcmg

Posted by: @derek-m

@webcmg 

Hi,

It would appear that your buffer tank has 2 input pipes and 4 output pipes, which is now making more sense. So what temperatures are you getting on the various pipes?

I don't have equipment to measure the temperature accurately (plumber did the last readings), but with an infrared laser thermometer I'm getting

UFH

• 20.3 flow
• 18 return

Radiators

• 21.4 flow
• 19 return

Flow temp on the programmer at the time was 33, target was also 33.

 

Hi,

Did you manage to resolve your problems? Feedback would be welcome.

Posted by: @derek-m

Posted by: @webcmg

Posted by: @derek-m

@webcmg 

Hi,

It would appear that your buffer tank has 2 input pipes and 4 output pipes, which is now making more sense. So what temperatures are you getting on the various pipes?

I don't have equipment to measure the temperature accurately (plumber did the last readings), but with an infrared laser thermometer I'm getting

UFH

• 20.3 flow
• 18 return

Radiators

• 21.4 flow
• 19 return

Flow temp on the programmer at the time was 33, target was also 33.

 

Hi,

I can't remember if you said yours is a newly installed system that has never performed correctly?

I have been working for while with a lady experiencing similar problems to yourself, and after numerous tests I'm coming to the conclusion that the main problem is associated with the water flow around the buffer tank.

If the water flow around the buffer tank is correct, then the temperature of the water flowing out of the buffer tank to your radiators and UFH, should be approximately the same temperature as the water flowing into the buffer tank from the ASHP. In the same manner, the return water from the buffer tank to the ASHP, should be at approximately the same temperature as the return water from the radiators and UFH going into the buffer tank. When the system is functioning correctly there should be a delta T of approximately 5C between flow and return temperatures.

As an example, if the water flow temperature coming from the heat pump is 35C, then the water going to the radiators and UFH should be approximately the same. The return water coming from the radiators and UFH should be in the region of 30C, as should the temperature of the return water to the heat pump. Any large differences would probably be caused by mixing within the buffer tank, which of course will affected the operation and efficiency of your system.

You could try measuring the temperature of the pipework around your system by using your IR temperature gun, but if you do not get meaningful results then purchasing one or two cheap temperature meters may be worthwhile.

@Derek-M what was the solution to this issue?

Hi @webcmg 

The ladies problem has not yet been fully resolved, to do so may mean alterations to the pipework around the buffer tank.

With your particular system I would suggest that you identify where the pipework around your buffer tank is connected, check for any closed valves and whether or not any pumps are running. Then measure the temperatures of the pipework and to try to ascertain where the water may be flowing.

Posted by: @derek-m

Posted by: @webcmg

Posted by: @derek-m

@webcmg 

Hi,

It would appear that your buffer tank has 2 input pipes and 4 output pipes, which is now making more sense. So what temperatures are you getting on the various pipes?

I don't have equipment to measure the temperature accurately (plumber did the last readings), but with an infrared laser thermometer I'm getting

UFH

• 20.3 flow
• 18 return

Radiators

• 21.4 flow
• 19 return

Flow temp on the programmer at the time was 33, target was also 33.

 

Hi,

Did you manage to resolve your problems? Feedback would be welcome.

Hi @derek-m - the plumber popped over today so was able to get some readings which are as follows:

Buffer
Flow 34
Return 31

Radiator circuit
Flow 34
Return 29

Radiator circuit (nearer buffer)
Flow 34
Return 31

UFH circuit without running radiators
Flow 31
Return 27

From ASHP to buffer
36 flow
33 Return

Radiator circuit when also running UFH
30 Flow
28 Return

Underfloor when also running Radiators
32 flow
28 return

All looks pretty normal?

@webcmg 

So what are the room temperatures?

Posted by: @derek-m

@webcmg 

So what are the room temperatures?

@derek-m It's hard to tell because it's been warmer outside (10 degrees today) and I had to put the heat curve up to 0.9 in order to get any heat in the rads. It's now been escalated within Vaillant because they've accepted that the system isn't operating as per their design specification (i.e. comfort at the right level of economy).

Posted by: @webcmg

Posted by: @derek-m

@webcmg 

So what are the room temperatures?

@derek-m It's hard to tell because it's been warmer outside (10 degrees today) and I had to put the heat curve up to 0.9 in order to get any heat in the rads. It's now been escalated within Vaillant because they've accepted that the system isn't operating as per their design specification (i.e. comfort at the right level of economy).

 

Hi,

What I meant is what is the actual temperature in the various rooms, and are they remaining reasonably constant or are they varying with the outdoor air temperature?

@webcmg why did you want heat in the radiators…the whole point of any heating system is to have warm rooms, NOT hot radiators!

Posted by: @alec-morrow

@webcmg why did you want heat in the radiators…the whole point of any heating system is to have warm rooms, NOT hot radiators!

Yes, but if the radiators aren't even warm... Then it's unlikely the room will be warm either. Quick update. Vaillant have been investigating, no real progress, no major changes proposed. Upstairs cold when it's cold outside. Seriously frustrated and disappointed.