Underfloor heating takes all day to heat up Read more.

[Pototea]

Hi, I'm a new poster here. I hope it's ok to ask for some advice as I've been banging my head for sometime.

I have a wet underfloor heating system with a grundfos multi head g pump.

I previously had a grundfos auto ump 3 auto l pump which was faulty and the plumber replaced it with the multi head g last month.

Previously the floor would get warm after 2 hours. Since the new pump was fitted, the floor only gets warm if the pump has been running 10 hours +.

The pump is set to 3 (max) setting. All other radiators get hot in the house so it can't be a boiler issue.

I'e noticed that this pump switches on and off very frequently. The temperature mixer at the pump is set to 45'c.

Does anyone have idea what could be causing the floor to take so long to heat up compared with the previous pump? Any help would be much appreciated.

[Pototea]

Thanks, this is really helpful.

The water pipe going in is hot.

I suspect an airlock might be the correct answer since the floor does eventually get warm after 10 hours although it is patchy and with the last few rows of tiles significantly colder than the first few rows.

The plumber did connect the mains to the pipework to get the airlock out but I'll get him to do it again as i don't think he pumped water through the whole circuit.

Thanks All,

[Pototea]

Hi there,

I just thought I would post an update to this.

First of all thanks everyone for your help and advice.

I decided to call another plumber in the end last week as I've had two months of extremely high gas bills and my floor was just not getting as warm as I remember.

It turns out that the plumber who changed the pump in January connected the wrong way round and it's been pumping water back up to the boiler and counter acting the boiler pump rather than pumping water into the UFH.

The new plumber I called looked at it and right away said that was the problem was. He fixed it and now I have an entire floor that heats up evenly and within 1.5 hours.

I called the old plumber to let him know. We do appear to have a problem with the boiler now in that the pressure keeps dropping. Everytime I fill it up the pressure drops back down half a bar from 1.5 to 1 the next day. The plumber came to take a look at it but can't figure out what is wrong with the boiler and suspects it's a leak somewhere. Sigh...

Lesson learnt, my instinct was right that something was wrong with my heating.

[Pototea]

Thanks all for the advice.

The boiler pressure seems to have remained constant for the past 2 days so I'll keep an eye on it and I think I'll call another plumber if it seems to have issues.

I have a 4 bed 3 storey mid terraced in London and my gas bills are typically £60/month based on actual meter readings. When they increased to £80/month and the floor wasn't getting hot I knew something was up despite the plumber telling me it was working as it should be so that's when I called a new plumber who detected the previous one fitted the pump the wrong way round.

All of the floor in the kitchen which is 35sqm gets warm after 1.5 hours and all tiles are evenly warm.

[Pototea]

I have mine set to 2 hours am and 2 hours pm at 21'c. I tried 24/7 at 19'c for a few days but this resulted in the heating only kicking in the middle of the night which wasn't when I wanted a warm kitchen.