A problem with carpet and underfloor heating- please help.

Hi,

Firstly, thanks for reading this post.

I have just bought a new build flat fitted with an NIBE F205P heat pump and electric underfloor heating (UFH). I always wanted to get a nice soft carpet fitted and I was aware of the combined underlay and carpet value not exceeding 2.5. However, I stupidly bought a combined Tog of 2.8 and it is already been fitted (muppet).

I have Duralay King (Tog 0.8) underlay (good for UFH) and Associated Weevers Invictus Sirius carpet (Tog 2.0). Naturally, this is preventing the heat to radiate up through into the room. For example, the small bedroom is set at 19 degress and its been sat around 15-16 for a few days. This is not ideal because one shouldn't let the temp fall below 16 when using UFH. The way I see it is that I can replace the underlay for Olympic 3 (Tog 0.3) or replace the carpet. The latter is clearly more exspensive given the league that the Sirius carpet is in. Replacing the underlay will bring the tog down to 2.3 which is good. However, I cannot determine whether this is going to be suitable because I discovered that the carpet has a fusion back. This is a combination of hessian and felt. Now felt backed carpet/underlay is not suitable for underfloor heating, although this is a fusion backing and the felt is INCREDIBLY light and not hard packed like one would typically expect in a more traditional felt backed carpet. However, can I simply view this pragmaticaly and just go by the tog rating of 2? After all this is what dictates the insulating capacity of the carpet. The other option is to keep the underlay and drop down to the Invictus Orion carpet which has a tog of 1.55. This then also brings the down to 2.35, although it still has this fusion backing so is it suitable really? As I said, the felt is so fine its almost non-existent, but you experts will no best.

It was a very stupid mistake to make I know. I have no reference point as to how much 0.3 togs will make. Clearly, that extra 0.3 does indeed make a HUGE difference. The sirius is a thick pile carpet- its proper lush. However, once again can I just view the tog rating and go from there. I do not want to buy anything else until I can be absolutely sure that I am making the right choice. If I don't replace either then clearly I am going to rack up a huge electric bill, despite the NIBE efficiency; and potential cause damage to the heating. Clearly its going to be getting very warm indeed under the floor!

Urgent help is therefore required.

Thanks folks.

John

 

Cant really help with the heating issue but what I will say is keep an eye on your sirius carpet because Ive fitted loads of it and the pegasus and in the last couple months ive had a few of my customers ring me to tell me the 'pile is coming away from the carpet' on investigating it seems Invictus seem to be suffering from a tuft issue and so far the complaints ive put in all 3 have been granted without any hassle. 1 customer opted for 50% compensation to close the complaint and live with the carpet, other 2 are in process of being replaced with a totally different carpet (their choice). It is a lovely carpet, feels great but im not pushing it anymore due to the hassle its given me. Its not just myself but ive spoken to a few others including a shop owner who has had exactly the same issues. Just thought id give you the heads up anyway.

 

Cheers mate- that might end up being a work around. However, I should probably get this sorted ASAP so I don't cause damage. Any idea on the Orion? Does that suffer too?

 

Definitely a problem with the ufh I would think as 2.8 tog is only just over the limit. I've recently finished a sizeable housing contract, I used cloud 9 radiance and cormar oaklands which was also about 2.8 tog, and the houses were getting red hot afterwards!

 

Yeah thats what I thought i.e. 2.8 isn't much higher. However, if the relationship between heat radiation in room and tog is not linear then it could be a major factor.

Anyway, the engineer came around yesterday and slowed the air flow down on the NIBE (heat pump system remember), and that has added 1-1.5 degrees. Basically it was too fast so the heat exchanger wasn't working efficiently by having enough time to extract the heat to recycle through the system. Nevertheless, it still is not up to scratch yet. Bedroom should have been 19 this morning and it was 17. I think what I might do is get some 3 and 5 mm underlay (0.3 and 0.5 tog) for UFH and swap out the underlay in small bedroom. Then I can test it. Just need to find somehwere that can provide me with 6.6 m2 on the cheap. The flat was proper toasty before the carpet went down so I doubt it is the UFH to be fair.

 

BTW, the engineer said that these heat pump systems (NIBE F205P) are so finely tuned that everything needs to be bang on. Apparently, work different from standard system as it is relying on recycling that warm air. If it doesn't generate the output, it cannot extract therefore resulting in a loss of inertia in the system.

 

Just an update on this. My mate needs his smaller apartment recarpeted so is going to be an absolute champion and buy the carpet off me. I figured there is no point having the Sirius carpet with a thin underlay. Going to swap it out for the lower tog Orion of 1.55. Hoping the new combined tog of 2.35 will be ok. Although I have read its best to get it down to 2 with heat pump UFH. It's only 0.15 below maximum threshold but 0.45 below the current value. That's quite a difference. I also spoke to Associated Weavers direct and they said the fine felt combined backing is just to help manoeuvring during fitting, therefore a pragmatic approach i.e. Just worry about the tog value, is all that's required. The heating is working. By comparison to the figures above, my mates heating just packed up and it was 11 degrees indoors. Hoping my choice will sort my problem but once again welcome feedback.

 

Just an update on this. My mate needs his smaller apartment recarpeted so is going to be an absolute champion and buy the carpet off me. I figured there is no point having the Sirius carpet with a thin underlay. Going to swap it out for the lower tog Orion of 1.55. Hoping the new combined tog of 2.35 will be ok. Although I have read its best to get it down to 2 with heat pump UFH. It's only 0.15 below maximum threshold but 0.45 below the current value.

 

Hi Folks,

I started this thread in 2016 and I have since changed the carpet so there is an underlay and carpet combined tog 2.1. It has not worked.

Since doing so, I have been in discussion with the contractors who installed it for the builders. It has taken ages to get any sort of progress which only revealed more confusing information. They arranged an independent thermal camera test which revealed that the bare naked wooden floor was only outputting 23 degrees. The independent chap informed me that if the system was designed to keep the rooms at 21 degrees, there would need to be a differential of at least 5 degrees meaning the bare floor needed to be 26 degrees. In that moment, the contractor who installed it revealed that the builder instructed them to install the heating “UNDERNEATH” the sound proofing.

Sorry but does that not sound like madness? Now I cannot predict what combined tog to install as clearly the heating is not producing the necessary heat, arguably because of the sound proofing being laid on top! I cannot even install hard flooring as it is against the terms of the lease.

I was thinking of contacting NHBC about this as I still have six years left and surely this is a building cock up. My flat is relatively small and my electric is £60 per month on average across the year. That is far too much for just me and it’s gonna seriously affect ability to sell. I really am in a quandary.

Any thoughts folks?

many thanks

John

 

Find out the type of soundproofing, normally it’s something like regupol, it’s dense rubber so surely will effect the transfer of heat into your room

 

Also it’s a air source pump isn’t it....... the model you have tends to use lots of electric so £60 a month is actually pretty reasonable

 

Hmmmmm, not when it produces no heat it isn’t. Last three month winter bill was £330 and i was barely achieving 19 degrees with the immersion boost mode on too. Still investigating the situation but thanks for your input.