Underfloor Heating Flow Rate/Valve

[TimJ1975]

Hi,

I have a new build with wet underfloor heating. Electrics have been done at first fix and plumber has been installing combi boiler, zone valves and connecting manifolds etc for underfloor heating. We have had the boiler running to help dry out the screed (albeit its been 8 weeks now so assume its reasonably dry).

The plumber was running the system off the boiler pump to test and try and get some heat into the build and the concrete floor was very warm but took an absolute age to get warm.

However this weekend I thought I would try and get the pump going on the manifold as the flow meters on the manifold showed zero. I also decided to purge the system by running water through the zones to clear any air pockets. When connected to the mains water the flow values show a high rate of flow.

However I expected when I start the manifold pump that the flow values would show more than zero and was hoping the floor would heat up quicker. But its not doing so and the boiler shows pump overrun intermittently.

This has made me wonder if the plumber has connected the flow and return correctly? The arrow on the pump is showing a different direction to the flow direction on the manifold and I also wondered if the blending valve was right too. I attach some picture which I am not sure will help but ask the forum a couple of questions.
1. Is the pump flow the right way round?
2. Is the supply to the blending valve correct?

The upstairs shows a good flow reading and works well. And the pump arrow looks aligned with the manifold flow.

Is the problem downstairs the pump flow direction?

Thanks
Tim

Untitled

• TimJ1975
• 15 Dec 2013
• 1

Untitled

• TimJ1975
• 15 Dec 2013
• 1

 

[Gasguru]

Provide a link to the U/F heating manufacturer

 

[TimJ1975]

Hi, Not sure who the manifold manufacturer is but I have seen this one for sale which looks very similar/same...
http://www.ebay.co.uk/itm/8-PORT-UN..._Hearing_Cooling_Air&var=&hash=item4acca7f740

 

[captainpp]

I think your pump is upside down. It should be pumping from the mixing valve towards the flow side of the manifold.

You have a very similar looking manifold and mixing valve to mine. The difference with mine is that the pump and mixing valve are on the left of the manifold with mine.

See for example here: http://media.cascade-uk.com/Pedarsons//reliance/cp14kwtech.jpg

Amusingly the pump is shown in two different directions in that link. The LHS image shows it correct (pumping up) and the two RHS images shows it incorrect (pointing down).

Similarly, see here: http://www.underfloorheatingsystems.co.uk/wp-content/uploads/One-Large-Zone-Instr.2.pdf. Here the pump is shown pumping up. (I could go and check mine, but it's in a loft and I'm too lazy!)