"....heat it with a candle, mate" - thoughts?

[Piers]

"You could heat it with a candle, mate" was what a visiting roofer told me recently. He thought we'd overdone it by installing insulation properly and (horror of horrors) taping joints.

 

But now I AM thinking about how to heat it (our PD outbuilding) and I'd hoping for some advice/tips/sales pitches/etc.

 

This is what it currently looks like:

 

:

 

It's about 55m2 inside - 3 rooms inc. open-plan workshop, yoga studio and a bathroom. Strictly incidental use as it's a PD building.

 

The building is too small for ASHP (IMO) and doesn't have access to gas. We're looking at ways to heat it with 'leccy.

 

Default idea was to stick some electric rads in.

 

But my Polish plumber has persuaded me to look at Termofol, infrared UFH. He tells me it's very popular in Poland. (https://termofol.co.uk/)

 

Has anyone used this stuff, or anything similar? Any good? Limitations? 

 

The other idea, which I'm a bit less keen on, is using wall-mounted infrared panels like those made by Herschel (https://www.herschel-infrared.co.uk/) and others. Has anyone tried these?

 

I'm really open to ideas on this.

 

And if nothing works out, I've always got a candle as a fallback....

 

[Stones]

£10 fan heater? Panel heaters or combination thereof? Heat as you need it, a space that size will not take long to get up to temp, and once activity starts, will stay warm.

[Jeremy Harris]

All UFH is primarily long wavelength infra red, as very little heat gets conducted into the air in the room directly from the floor.  There seems to be a bit of a trend to advertise heating as being IR, as if it's something novel, when the reality is that any fairly low temperature heat source that doesn't use forced air is going to heat largely by long wavelength radiated heat.  There's a relationship between surface temperature and peak emitted wavelength, but frankly there's not much of a difference for temperatures within the normal range for domestic heating systems.  For example, UFH with a floor surface temperature of 24°C will radiate at a peak wavelength of about 9.75µm, UFH with a floor surface temperature of 30°C will radiate at a peak wavelength of about 9.56µm.   A radiator running at 60°C radiates at a peak wavelength of about 8.7µm, so not a lot different from UFH in terms of IR wavelength (the long wavelength IR band ranges from about 8µm to 15µm).

 

It doesn't matter, in terms of infra red radiated heat how the floor is heated, the only real consideration is how efficient and cost-effective any means of heating will be.  For your design, raised on piers, the heat loss rate from any UFH systems will be a bit higher in cold weather than that from a heating system that doesn't rely on heating an internal surface to a higher than room temperature, just because the temperature differential across that part of the building will be higher.

 

Direct electric heating will be close to the most expensive way to heat the building, and direct electric floor heating will be more expensive to run than electric heating that doesn't heat an internal surface, but whether that matters really depends on the balance of installation cost versus typical running cost through life.

 

 

[ProDave]

Why is it too small for an ASHP?  Seek out a cheap one on ebay and DIY install it with some under floor heating.  the HP won't be complaining  that it does not turn on much.

 

P.S I would be wanting some diagonal bracing on those longer front legs that it is standing on.

[SteamyTea]

Air to air heat pump, get some cooling too.

My house is just a bit smaller than yours, but terraces, and in the warm SW.

I use storage heaters in E7. Don't usually need more than about 10 kWh/day.

Small A2A would easily do that.

[Ferdinand]

44 minutes ago, Piers said:

55m2 inside

 

How did you get 55 sqm under PD?

 

On the heating, why not some sort of reversible "single room" split heat-pump type thing? You may need cooling as well as heating - heat soak etc. Also, how well is it actually insulated - whether Regs standard or say much better will be pertinent imo?

 

Ferdinand

 

Edited August 3, 2019 by Ferdinand

[Onoff]

Any pics of the timber frame construction supporting everything? As in pre the floor going on. Might help @zoothorn on here who's aiming for something similar on his stream bank.

 

+1, I thought 30m2 was the limit?

 

Tbh I'd have expected it to have been built on piers... 

[PeterW]

9 minutes ago, Onoff said:

thought 30m2 was the limit

 

It is for exempt from Building Regs, there is no limit on an outbuilding which is used as incidental to the main dwelling house assuming :

 

 

Outbuildings are considered to be permitted development, not needing planning permission, subject to the following limits and conditions:

- No outbuilding on land forward of a wall forming the principal elevation.

- Outbuildings and garages to be single storey with maximum eaves height of 2.5 metres and maximum overall height of four metres with a dual pitched roof or three metres for any other roof.

- Maximum height of 2.5 metres in the case of a building, enclosure or container within two metres of a boundary of the curtilage of the dwellinghouse.

- No verandas, balconies or raised platforms (a platform must not exceed 0.3 metres in height)

- No more than half the area of land around the "original house"* would be covered by additions or other buildings.

- In National Parks, the Broads, Areas of Outstanding Natural Beauty and World Heritage Sites the maximum area to be covered by buildings, enclosures, containers and pools more than 20 metres from the house to be limited to 10 square metres.

 

That is from the planning portal. 

 

 

 

[Onoff]

24 minutes ago, PeterW said:

- In National Parks, the Broads, Areas of Outstanding Natural Beauty and World Heritage Sites the maximum area to be covered by buildings, enclosures, containers and pools more than 20 metres from the house to be limited to 10 square metres.

 

Ta. That last bloody one gets me, us being AONB!

[Russell griffiths]

Plus one for looking at those front legs, triangulation needed on those I would have thought. 

[Piers]

21 hours ago, ProDave said:

P.S I would be wanting some diagonal bracing on those longer front legs that it is standing on.

 

19 hours ago, Russell griffiths said:

Plus one for looking at those front legs, triangulation needed on those I would have thought. 

 

Yes, absolutely. They're going to be braced.

 

21 hours ago, ProDave said:

Why is it too small for an ASHP?  Seek out a cheap one on ebay and DIY install it with some under floor heating.

 

I just remember someone telling me that ASHP doesn't really make sense for a building of this size. I was also told that because the floor is timber and suspended off the ground, we won't have an awful lot of thermal mass to heat using UFH (and to retain heat after the UFH goes off). I think that's what @JSHarris is saying too

21 hours ago, JSHarris said:

For your design, raised on piers, the heat loss rate from any UFH systems will be a bit higher in cold weather

 

21 hours ago, JSHarris said:

Direct electric heating will be close to the most expensive way to heat the building, and direct electric floor heating will be more expensive to run than electric heating that doesn't heat an internal surface, but whether that matters really depends on the balance of installation cost versus typical running cost through life.

 

Are you saying that, as the lesser of two evils, direct electric rads are going to be cheaper to run than direct electric UFH?

 

21 hours ago, SteamyTea said:

Air to air heat pump, get some cooling too.

@SteamyTea, what kind of A2A have you got? 

 

Something like this: //www.appliancesdirect.co.uk/p/iqool-2ms9k9k/tcl-iqool2ms9k9k-air-conditioner

 

[PeterW]

55 minutes ago, Piers said:

Something like this: //www.appliancesdirect.co.uk/p/iqool-2ms9k9k/tcl-iqool2ms9k9k-air-conditioner

 

Check this thread where @JSHarris installed a precharged A2A 

 

 

[SteamyTea]

55 minutes ago, Piers said:

what kind of A2A have you got?

I haven't.  I did think of getting one, as @JSHarrissent me a link to a Panasonic one that was pretty cheap.

But when I sat down and worked it all out, I decided that I would stick with my storage heater for a little longer.  Storage heaters are just so reliable and I only need them for 6 to 10 weeks of the year usually.  Some years I have just used a £10 fan heater.

The only thing with an airthight house is that if you go away for a few weeks and leave the heating off, damp can become a problem.

I fancy fitting MVHR, so that would sort the problem out.

[Jeremy Harris]

@Piers, As @PeterW suggests above, fitting one of these air-to-air units is pretty straightforward. 

 

I have a vacuum pump and gauge set you can borrow if you wish, makes sure that the pipes etc are completely dry inside and leak tight before the refrigerant is released into them from the outdoor unit.

[Jeremy Harris]

1 hour ago, Piers said:

 

Are you saying that, as the lesser of two evils, direct electric rads are going to be cheaper to run than direct electric UFH?

 

 

Yes, electric radiators will be cheaper to run than electric UFH.  All UFH heats the floor surface and so makes the floor warmer than the room.  This means that the differential temperature from the floor surface to the underneath of the floor structure will be higher, so the heat losses will always be higher with UFH.  Usually this isn't much, around 10% or so, but it does make an expensive heating "fuel" even more expensive to run.

[ProDave]

1 hour ago, Piers said:

I just remember someone telling me that ASHP doesn't really make sense for a building of this size. I was also told that because the floor is timber and suspended off the ground, we won't have an awful lot of thermal mass to heat using UFH (and to retain heat after the UFH goes off). I think that's what @JSHarris is saying too

 

There is no such thing as "thermal mass"

 

Our house is all timber, and retains heat incredably well.  As well as specifying a lot of insulation, the type also has a big effect.  Ours is a mixture or wood fibre and Rockwool type (earthwool)  These and things like celulose as well, have a long Decrement Delay, which is a way of saying it takes a long time for heat to work its way through the walls.  Other types like PIR (Kingspan etc) have a much shorter decrement delay.

 

Our house is such that if you turned the heating off it would be something like 2 days in winter before you noticed.  It certainly does not cool down a noticable amount overnight.

 

If you do go UFH try and get more insulation under the floor to minimise losses.

 

What sort of type and thickness of insulation are you planning?

[SteamyTea]

7 minutes ago, ProDave said:

There is no such thing as "thermal mass"

I have been running an experiment for over a year now, just three boxes, exposed to the weather, with the same volume of different masses in them.

This does not model a house, but shows that during cold spells, there is effectively no difference.

Hot spells are a bit different.  Mean temperature days are so variable that it is hard to draw a conclusion from temperature differences alone.

Below are the coldest day and the hottest day charts.  Lots of variation on the hottest day.

 

[SteamyTea]

Just to highlight the variation of 'normal days'.  The charts below all have the same external air mean temperature, within 0.1°C.

I shall restate, this is not modelling a house.