ASHP Costing £40 a day and cold upstairs

[Radian]

1 hour ago, GrantMcscott said:

I currently can not use the master bedroom as it is to cold but it is a big room with lots of glass.

Given that you also say you have no carpet, I doubt if you have curtains either. Unless triple glazed with low-E glass, large windows will have a noticeable cooling effect on your skin as your body heat radiates away. To an extent this is also cooling the fabric of the room as well so the easy win here is curtains.

[Bozza]

2 hours ago, Onoff said:

 

Does an MVHR compensate for a too airtight build?

I think it would.  But not in my case as I didn’t put MVHR in

[Ferdinand]

Sorry to hear your challenges, @GrantMcscott.

 

There's been quite a bit of nodding to theory on this thread (which is important). FWIW, your floor spec is - to my eye - pretty good rather than reasonable. By ufh only has 90mm of PIR under it, but was built in 2009. Your 150mm will on its own meet the current building regs newbuild value of 0.13 in England, which was not pushed further in the latest update in June 2022, and looks to be here to stay.

 

My suggestion is to get an inexpensive thermal camera, and take a pretty comprehensive set of photos outside and inside whilst it is cold out and and warm in, which will show heat leaks (including warm outward draughts) well. You should also see useful cold spots etc with photos taken inside.

 

Once you have that data then you can decide what to do next.

 

Simple tools you may also find useful are things like (sample sources):

 

A £5-10 hand held point and shoot thermometer:

https://cpc.farnell.com/duratool/d03308/infrared-thermometer/dp/IN08363

 

A couple of £10 or so min/max thermometer / hygrometer

https://www.amazon.co.uk/Digital-Thermometer-Hygrometer-Temperature-Humidity/dp/B00VYRC58I/

It's he simplest form of data logger ! I always have a couple of these around for quick checks.

 

Then you could have a simple datalogger recommended by one of the BH co-conspirators.

 

My house is a little smaller than yours - 200sqm, but I live here on my own (with the squirrels and the foxes) and my energy bill in December is also going to spike. I've been running a couple of rads only (24x7 for some of it which I have just cracked down on), and closed down all the bedrooms except one. Are there any parts of yours you can seal off for the winter, to reduce the volume heated?

 

I don't know about your wood supplies, but have you considered running your woodburner overnight in a damped down mode?  

 

One other thought - are you on an optimal electricity tariff for your heating strategy? What would happen if you switched to a cheap overnight tariff and ran the UFH heavily then, and relied on the slab-heat-delay plus wood burner to keep you warm in the day?

 

ATB

 

Ferdinand

[GrantMcscott]

I still have some windows on one side of the house that needs timber clad that has not been done yet.  The windows have been sealed with expanding foam but what tape would you use to seal them to the building before clading?

 

Also no rendering has been done yet so is there anything I can do to make them more air tight before the building is finished?

[SteamyTea]

8 minutes ago, GrantMcscott said:

Also no rendering has been done yet so is there anything I can do to make them more air tight before the building is finished

What has been used as the vapour control layer?

That should keep cold air out, even if the insulation is being bypassed in places.

[Onoff]

12 minutes ago, GrantMcscott said:

The windows have been sealed with expanding foam but what tape would you use to seal them to the building before clading?

 

For example. The tape I'm on about, colloquially called "compriband", whatever the make, expands massively to fill the gap. You can get it adhesive one side that you stick to the window frame JUST before it goes in. Or tape you push in afterwards.

 

 

 

[Radian]

7 hours ago, Ferdinand said:

FWIW, your floor spec is - to my eye - pretty good rather than reasonable.

That was my comment. Given that UFH pipes have a flow temperature greatly in excess of what we tend to think about with insulation in other places, building regs don't discriminate (AFAIK) between losses at ambient and the directly heated screed. Therefore going beyond regulation minimum would seem to be sensible.

[PeterW]

@GrantMcscott have you had an air test done ..?

 

You need to tape the inside of the frames - cut the reveal back, tape the window over the foam (cut it flush) and then use an 80/20 tape to seal the whole window. Then re-board and skim. 

[Thorfun]

2 hours ago, GrantMcscott said:

I still have some windows on one side of the house that needs timber clad that has not been done yet.  The windows have been sealed with expanding foam but what tape would you use to seal them to the building before clading?

 

Also no rendering has been done yet so is there anything I can do to make them more air tight before the building is finished?

I’m sure someone will correct me if I’m wrong but this sounds like you want to airtight outside the windows before cladding/rendering. Your airtight layer is internal. The outside of the building needs to breathe. 
 

I guess I could’ve got the wrong end of the stick for what you’re talking about here though. 

[GrantMcscott]

16 hours ago, Onoff said:

 

For example. The tape I'm on about, colloquially called "compriband", whatever the make, expands massively to fill the gap. You can get it adhesive one side that you stick to the window frame JUST before it goes in. Or tape you push in afterwards.

 

 

 

The windows are sitting mostly in the 50mm cavity so there is hardly anything for the compriband to stick to.  I was looking for a tape to tape the window to the timber frame 

[Onoff]

15 minutes ago, GrantMcscott said:

I was looking for a tape to tape the window to the timber frame 

 

I assume you mean on the inside? That second Illbrück video I link above shows taping the window to the frame. Starts about half way through.

 

As for foam then the Illbrück FM330 stuff stands head and shoulders against all the other foams out there imho. 

 

"hardly anything for the compriband to stick to"

 

It really doesn't need much of an unsealed gap to lose heat / get a draught through. 

[Radian]

2 hours ago, Onoff said:

Illbrück FM330

Blimey - an umlaut and all! Is toolden' pack of 12 for £119.99 the best price for these?

[Onoff]

44 minutes ago, Radian said:

Blimey - an umlaut and all!

 

As with airtightness, the Devil is in the detail! 

[Miek]

2 hours ago, Radian said:

Blimey - an umlaut and all! Is toolden' pack of 12 for £119.99 the best price for these?

More or less the best price. Cheap compared to compriband which is silly money. These things are mostly used on expensive windows so the price kinda pales in comparison to the glass. 

[Thorfun]

2 hours ago, Radian said:

Blimey - an umlaut and all! Is toolden' pack of 12 for £119.99 the best price for these?

i bought mine from ebay (https://www.ebay.co.uk/itm/333714806299) but they were only £104.99 at that time. have gone up a tenner since.

[Radian]

15 minutes ago, Miek said:

These things are mostly used on expensive windows so the price kinda pales in comparison to the glass. 

Good observation. I will do absolutely everything in my power to avoid being taken for a mug like that.