Hi when i went to raise the temp on the mixing valve you could feel the temp rise on the mix pipe until it went past the 5 mark then stayed at roughly the same temp all the way up to 10 mark. Thinking this was a fauty mixer i took it back to the supplier who told me the return side into the valve was getting too big a pressure and forcing the temp down in the mix and to put a valve on to restrict the return flow into the mixer. This seemed to work but to get the temp up now the flow indicators on the manifold barely register even with the pump set to max. Pump was supplied with system so should be large enough. Any help appreciated.
This was a self install and the pump is fitted on the mix side of mixer.
View attachment 4468View attachment 4470View attachment 4471View attachment 4469Sure. there are 2 manifolds. 1x upstairs & 1x downstairs. Both are having the same problems. Downstairs the pump is beside the manifold but upstairs the pump & blending valve are 10m from the manifold.
Flow and return to the manifold upstairs is in plastic pipe.
Not sure of the make of valve it has either a W or M stamped on it depends which way up its supposed to be. My boiler (Guntamatic 27kw pellet boiler) is set at 75 degrees and feeds 1000l buffer tank to supply ufh. The valve should be installed correctly with flow (hot water ) to + and cooler return feeding - . I also have a problem when colder weather hits that when the heating comes on it drains the buffer quite quickly as you would expect but instead of the boiler spinning up to cope with this it sits around 30% output. Thie guy who installed the boiler said to restrict flow to the buffer and it should draw from the boiler instead which it does seem to do but i think that because i cant get a good flow rate to the manifolds it still seems throttled down when i think it should be giving a higher output. I have been wondering for a while whether the circulating pump for the boiler is too small and cant clear the water out of it quickly enough and it is shutting down because its at temp.pump is on return.
Yes i did make it myself but it was to supplied schematics.
have upped the boiler temp to 80 now and opened the restricter valve to the mixer which has given me some more pressure but has still dropped the temp to the ufh even with the mixer opened fully
Ok heres an update, i have fitted 2 shunt pumps on the flow to the blending valves, sorted!!. I thought that the flow from the boiler had to be too low and the manifold pump was pulling in the return water through the blending valve instead of hot. The shunt pumps boost the hot flowrate and therefore pushs the hot through the blending valve which means i can open the restricters from the return and now have a good flowrate around the circuits. Toasty. When i fitted this system neither the boiler schematics or ufh schematics showed a shunt pump and the supplier said i didnt need one so just goes to show even the experts can be wrong. Hope my experience / inexperiance can serve to solve a similar problem for someone else
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