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.

[Paul Drawmer]

I am guessing. Might it be an airlock preventing proper circulation?

[Happy Jim]

Check the flow indicators are actually showing a flow (if not he may have left the valves closed by accident)

Jim

[Andehh]

Does the pump get hot? Does the pipe in get hot? Pipe out get hot?

[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.

[Welshbeef]

Our UFH from off to toe tingling hot is 2-3 hours.

2 hours gets it to a nice temp

[Blue62]

Pototea said:

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.

That sounds like quite a big leak to me, could it be that you're losing the water somewhere around the boiler, be surprised if you had a leak in the system. Others will know more than me, in my last house we dealt with a small leak by running sealant through, something we had to repeat every couple of years and not ideal. Good luck.

[Welshbeef]

Have you checked each and every radiator for air locks keep doing this as it might be 1 that’s causing it.

Check all visible pipes rub hand along each checking for wetness.
Any sign of wet/drying patches anywhere along where the pipes go?

You could turn off each and every radiator which when all done means you’ve only the pipes with water flowing round them. If the pressure holds then you know it’s not a pipe issue. It could be any of the valves or the radiators.
Next turn on one radiator test system for pressure loss - I guess this might take a week or more but in doing it this way you can narrow it down to 1 or more radiators / valves which are causing the problem.

This test costs you nothing no intrusive damage and a week or so later it MIGHT give you the source of the problem.

Good luck.

[GhostyDog]

Welshbeef said:

Our UFH from off to toe tingling hot is 2-3 hours.

2 hours gets it to a nice temp

Bloody hell, mine doesn't, but then I don't think it was fitted right, knew nothing about ufh before buying the house, learnt lots since... borrowed a thermal imaging camera from work and found loads of lazy loops, rather than coils.

As a result some rooms never get to target temp, and my gas consumption is ridiculous.

Thinking of getting a ground source system to augment the ufh...

GD

[Welshbeef]

GhostyDog said:

Bloody hell, mine doesn't, but then I don't think it was fitted right, knew nothing about ufh before buying the house, learnt lots since... borrowed a thermal imaging camera from work and found loads of lazy loops, rather than coils.

As a result some rooms never get to target temp, and my gas consumption is ridiculous.

Thinking of getting a ground source system to augment the ufh...

GD

As an example our place is 220m2 - hot water is on 24/7 and UFH was set to 25 degrees all Oct to Mar.
Average monthly electric and gas is £150pcm

[GhostyDog]

Welshbeef said:

As an example our place is 220m2 - hot water is on 24/7 and UFH was set to 25 degrees all Oct to Mar.
Average monthly electric and gas is £150pcm

I'm about 300m2, i've turned heating off now, but my bills were £240 a month, i've just switched to e.on who project it being £160 a month.

I dunno how much ground source would bring that down, but i've got a massive garden we ate having landscaped and i'm thinking of having the ground source put in then.

[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.

[Lanby]

Hi,
I know we are coming into summer now, but how do you guys set the timers for UHF?
Do you leave it on the same temp 24/7 or set the timers to make it warmer/cooler a couple of hours before it is required?
And which is the cheapest way to run it?
cheers

[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.

[Ranger 6]

Lanby said:

Hi,
I know we are coming into summer now, but how do you guys set the timers for UHF?
Do you leave it on the same temp 24/7 or set the timers to make it warmer/cooler a couple of hours before it is required?
And which is the cheapest way to run it?
cheers

We have a multiple setting timer so it's low through the night and warms up for breakfast and lunch times, then the evening. Weekends are a different timing profile and it works for us. If I'm working from home I'll just flick it on for an hour if necessary. UFH has been fitted for 10 years.

[Timmy40]

GhostyDog said:

Welshbeef said:

Our UFH from off to toe tingling hot is 2-3 hours.

2 hours gets it to a nice temp

Bloody hell, mine doesn't, but then I don't think it was fitted right, knew nothing about ufh before buying the house, learnt lots since... borrowed a thermal imaging camera from work and found loads of lazy loops, rather than coils.

As a result some rooms never get to target temp, and my gas consumption is ridiculous.

Thinking of getting a ground source system to augment the ufh...

GD

Interesting! I went for wet radiator gas CH, with electric UFH. The electric get the floor nicely warm within about 15min, that's all I use it for a comfy floor to walk on in the morning, the rads do the bulk heating of the air in the room. As a combo it works really well.

[Lanby]

Ranger 6 said:

We have a multiple setting timer so it's low through the night and warms up for breakfast and lunch times, then the evening. Weekends are a different timing profile and it works for us. If I'm working from home I'll just flick it on for an hour if necessary. UFH has been fitted for 10 years.

That mirrors what we do but I never know if it's the economical way to do it
Cheers

[Ranger 6]

It's certainly not expensive

[C70R]

Timmy40 said:

GhostyDog said:

Welshbeef said:

Our UFH from off to toe tingling hot is 2-3 hours.

2 hours gets it to a nice temp

Bloody hell, mine doesn't, but then I don't think it was fitted right, knew nothing about ufh before buying the house, learnt lots since... borrowed a thermal imaging camera from work and found loads of lazy loops, rather than coils.

As a result some rooms never get to target temp, and my gas consumption is ridiculous.

Thinking of getting a ground source system to augment the ufh...

GD

Interesting! I went for wet radiator gas CH, with electric UFH. The electric get the floor nicely warm within about 15min, that's all I use it for a comfy floor to walk on in the morning, the rads do the bulk heating of the air in the room. As a combo it works really well.

This is the same approach I took. Electric UFH is an absolute dream, and as you say heats up from stone cold to roasting hot in less than 20min in the winter. The other thing I've found is that it's such an effective system that the large room doesn't require heating, other than a small towel rail for drying bath towels.
I didn't do the maths on how the running costs compared with Gas UFH at the time, but it actually seemed cheaper to install (from memory) and I love the ability to have it run independently from the Gas CH.