Underfloor heating pump switching off after 2.5 hours and floor not getting warm

14 Feb 2007
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United Kingdom
Hi there,

I have a wet underfloor heating system in my kitchen (35sqm) which is causing problems.

I had a grundfos auto upm3 l pump which was displaying pump blocked message. The deblocking screw was damaged so the whole pump was changed 2 weeks ago.

The plumber fitted an older grundfos pump 2 weeks ago but i still have a problem, not sure if it is the same problem. He is coming back to take a look but i wanted some advice in case he is barking up the wrong tree.

For the new replacement grundfos pump which i forgot the model number:

1) We put the underfloor heating on for 30 hours. The first 3 rows of tiles get warm but not the rest of the kitchen. The pump goes on and off every 2-3 hours. Sort of like it gets to a certain temperature, switches off to cool down then comes back on again.

2) I've set the heating to normal program of 3 hours am and 3 hours pm. The floor is not stone cold but certainly not warm, I still need slippers. The pump shuts off after ~2.5 hours. The pipes going into the pump are very hot until it switches off.

Normal radiators which are on a different zone work fine. The previous pump, when it worked, would heat up whole kitchen after being on 2 hours.

Can anyone advise what the problem could be?

1) Pump is inside a cupboard. Could it be over heating which is why it switches off after 2.5 hours?

2) why does my floor not get warm after 2 hours? Could it be a flow setting? Or the new older version pump is not powerful enough for my kitchen size?

3) if I leave the heating on 30 hours why do only the first 3 rows of tiles get warm?

Any help would be much appreciated!
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