@webcmg 

Without seeing details of what the devices are I can only speculate, though I doubt they are indicating a flow of 2.5 to 3 litres per minute.

How many pipes are connected to your buffer tank? A photo would be useful.

@webcmg

Do you have any motorised valves like this leading to the radiators and do those pipes feel warm or cold?

Posted by: @colin

@webcmg

Do you have any motorised valves like this leading to the radiators and do those pipes feel warm or cold?

 

@colin not that I can see, just a grundfos pump set to level 3 (fastest)

@derek-m - here are some photos of the buffer tank. There are four pipes connected to the buffer - flow and return for UFH (the top two) and flow and return for the upstairs radiators (bottom two). There only seems to be one pump for the radiators. The UFH system has two manifolds which also have pumps for these sections. The flow device is also pictured (not active but when it's on the "plunger" drops to 2.5 - 3).

Posted by: @webcmg

Posted by: @colin

@webcmg

Do you have any motorised valves like this leading to the radiators and do those pipes feel warm or cold? 

 

 

 

 

@colin not that I can see, just a Grundfos pump set to level 3 (highest speed). Pipes feel cold when the UFH is on and warm when it isn't. That valve is for the DHW circuit. The system seems to turn the heating circuit off when the DWH comes on. The UFH pump is set to level 1 (lowest speed).

@derek-m - here are some photos of the buffer tank. There are four pipes connected to the buffer - flow and return for UFH (the top two) and flow and return for the upstairs radiators (bottom two). There only seems to be one pump for the radiators. The UFH system has two manifolds which also have pumps for these sections. The flow device is also pictured (not active but when it's on the "plunger" drops to 2.5 - 3).

First picture uploaded was a bit small.

@webcmg normally on a buffer the hottest heat requirement is at the top for obvious reasons.

so the floor should be at the bottom, radiators at the top that said I can’t actually see it in the photos

VR 71 and 70s are wiring centres to control circuit pumps and valves. Connection one of these to a sensor comfort reveals a whole lot more.

@alec-morrow you can see it here. The rads are definitely coming off the bottom two. If switched, won't that mean the UFH is too cold though given the rads aren't even warm to touch?

Also, on that basis shouldn't the inflow from the ASHP go into the bottom of the buffer rather than the top as setup?

@webcmg if the floor is screed with tiles the flow temp only needs to be 20-27c 

radiators do release heat at low flow temps but in your case not enough

@webcmg 

I think that you will find that the last photo shows the flow regulation valves for the different sections of UFH, which are indicating litres per minute.

The buffer tank would normally have 4 pipes connected, the water flow and return from the heat pump, and the flow and return to the heat emitters. The flow pipes would be connected at the top of the buffer tank, one on either side, with the return pipes connected at the bottom of the buffer tank, again one at either side. The warm water from the heat pump goes into one side of the upper section of the buffer tank and flows out of the other side to the heating system. The return water flow from the heating system goes through the lower section of the buffer tank in reverse direction to the flow.

It would probably be easier to understand if you trace out the pipework and check it against any diagrams shown in the manual.

If your heating system is functioning correctly the water in the flow pipes should be at a temperature approximately 5C above the return water temperature.

@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?

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.