New UFH wrong side of pump ?

[ShaunCorbs]

Try screwing the flow meters in might be all on max / fully open

 

[Locoblade]

Yeah I re-pressurised with a hose and purge out any air.

On the other side of the flow pump on the manifold there is a temperature gauge this is what spikes it’s like the mixing valve isn’t regulating the temp of the water coming into the manifold.

When I ran the new flow to the other side of the pump in the loft I didn’t change the return this still goes into the boiler return into the untilty could this cause a problem because the flow and return are about 10m apart?

Interesting, I've also got a Wunda manifold with their Salus auto balancing actuators and I'm also seeing unusual temperature spikes at the manifold that I'm trying to rectify.

I installed a cheap Wifi thermostat to tuck into the manifold inlet temperature probe pocket replacing the little gauge so I could see a graph of what it was doing through the day and what's happening with mine is from cold when a UFH zone first calls for heat I get an initial spike in manifold inlet temperature to about 55-60c for maybe a minute, despite the blend valve being set to 35c. After a minute or so the temperature reduces but how far it drops is dependant on what/how many zones are calling for heat. If there's only one small zone running the inlet temperature refuses to drop below about 50c. If another zone comes on the temperature in the manifold drops to around 40c (it never actually gets as low as 35c even when all zones are open), but shut it back down to one small zone and it goes back up to around 50c. So, everything seems to point towards the blend valve bleeding in too much hot water for the amount of flow around the loops.

I went through this with Wunda support and they sent me a replacement blend valve but fitting that hasn't improved things. If I dribble hot water through the flow side of the spare valve manually you can see it closing up as it gets warmer because water starts exiting out of a different hole so it seems to be functioning to a degree albeit not under pressure. Also if I turn the blend valve on the manifold from 35c to say 40c the manifold temps also climb about 5c so it is doing something with the incoming water.

The last correspondence I had with Wunda they were suggesting it's likely a heating design issue talking about the bypass circuit not doing it's job but I don't buy that (I don't think the bypass should need to do it's job if the system was working correctly) and given their tech tried to tell me the blend valve was basically just a tap you open more or less to allow more hot water in with no thermostatic element reacting to temperature I kinda lost faith at that point but my feeling is there's an issue with the way their valve works being overwhelmed by the incoming flow/pressure and is opening when it shouldn't do.