Heating empty new build house from cold

[Rajiv Patel]

Hi

My house is a detached house with 2 floors and 3 bedrooms. Currently I don't live there permanently because I'm still sorting out a few things so am living at my parents house. I probably go to the house once a week at the moment to sort out odd bits. What I'm finding is that the home heats up fairly quickly but loses heat fairly quickly. Here are some bits of info/questions

- I have Evohome installed so can check the temperature when away
- Leaving the heating off completely in the last week (5 deg emergency), the home dropped to 7 deg - is it normal for this to happen?
- I went there yesterday and it took maybe 3 hours to get from 7 up to 20 which i think is decent. Is that reasonable?
- However, I left and turned the heating off and overnight (over about 7 hours) it dropped to 14 degrees. This seems an extreme drop to me. Does this seem normal to you?
- It's new build so I expect it to have decent insulation and the insulation was checked during a survey and was "up to standard"

My parents house is a 2 bed terraced (middle of row) about half the size. This is constantly lived in and I find that the temperature here only drops around 2-3 degrees overnight. Admittedly it has fewer windows.

Does the fact that I'm not constantly living in my house make a big difference? So I'm not heating up the "fabric" of the house. I'm heating it up one day and then letting it get completely cold. I'm just trying to ascertain whether I have a heating issue or if what I'm experiencing is relatively normal given the circumstances. Maybe my expectation is too high given that I'm used to my parents house which is a bit smaller, terraced and has much fewer windows.

Any advice would be great!

 

[CBW]

Temp dropping over 7 hours seems normal to me, how much heat retention did you expect? Do you have flooring down yet?

 

[Rajiv Patel]

Temp dropping over 7 hours seems normal to me, how much heat retention did you expect? Do you have flooring down yet?

Yeh I have flooring. It's amtico downstairs and carpet upstairs. I do find the floor downstairs feels cold on the feet - particularly the living room.

I was expecting a temperature drop of maybe 2-3 degrees overnight. Admittedly this is based on the experience in my parents home which may not be a realistic expectation.

Do you think not living there constantly and having the home "fully heated" makes much of a difference?

 

[big-all]

remember the fabric off the building will still be cold so sucking in heat
when in use the fabric will radiate heat when heating is off
now it wont be a lot off difference but will make some difference

 

[Rajiv Patel]

remember the fabric off the building will still be cold so sucking in heat
when in use the fabric will radiate heat when heating is off
now it wont be a lot off difference but will make some difference

Thanks for this. I've read a few things about the "fabric" of the building. What exactly does this refer too? Is it just the walls and structure?

 

[JohnD]

Your insurers probably say the house should be heated to 12C while it is empty, 24 hours a day. This will prevent damp and freezing of pipes.

This actually quite cheap because daytime temps are often around 10C. It will prevent the walls getting cold.
If you have windows, the sun will add warmth on clear days.

If you have a concrete ground floor it will take a very very long time to get less cold. Warm air rises so will not heat the floor.

 

[Rajiv Patel]

Your insurers probably say the house should be heated to 12C while it is empty, 24 hours a day. This will prevent damp and freezing of pipes.

This actually quite cheap because daytime temps are often around 10C. It will prevent the walls getting cold.
If you have windows, the sun will add warmth on clear days.

If you have a concrete ground floor it will take a very very long time to get less cold. Warm air rises so will not heat the floor.

Thanks for this. I did initially keep the heating at 15degrees but found it was using a lot more gas than I was expecting. It has been quite cold the last month or so I guess which is why I turned it off to an emergency temperature of 5C.

As for the concrete floor, do you expect that this eventually heats up over time when living there?

 

[Harry Bloomfield]

- However, I left and turned the heating off and overnight (over about 7 hours) it dropped to 14 degrees. This seems an extreme drop to me. Does this seem normal to you?

A great deal will depend upon the outdoor temperatures and heat loss. My occupied home, heated during the day to maybe 19.5C generally, with heating set back at 11pm, might fall to around 18.5C by next morning. I have it setback to come on at 14.5C overnight, should it ever need to. Its a 1955 semi, which I well insulated and already had a lot of fabric able to store heat, then I added several more tons of such fabric.

Modern houses have a much lighter structure, so unlikely to store much heat, so I would suggest falling down to 14C over 7 hours is probably correct. You will find out for sure when you have moved in and actually need heat to be on, from your bills.

The 3 hours to heat up seems excessive if the building fabric is lightweight, I would expect my place to warm up from cold, un-lived in, within an hour.

 

[big-all]

the "fabric off the building" in this instance is everything the internal side off the insulation
brick plaster concrete or stone will absorb and hold more heat than say wood

 

[JohnD]

I wonder if you have curtains.

A new or empty cold house can take weeks for the walls to warm up. If it is newly built the walls may have been exposed to rain and cold before the roof went on.

If you have a timber frame house, or dot and dab plasterboard, the walls will not absorb much heat.

The 3 hours to heat up seems excessive

the radiators might be meanly sized?

 

[ericmark]

I found mothers house held the better than this one, her house off at 10 pm on at 7 pm and it was set to drop 20°C to 16°C but it rarely dropped 17°C, heating was a problem, set it to heat to 24°C at 7 am and reduce to 20°C at 8 am and the TRV heads would actually heat room to 20°C, however set to 20°C and it would not get to 20°C until around 10 am, the anti-hysteresis software in the TRV heads was a little OTT. Her house built 1954 and insulated.

Our house would warm up faster but also cool down faster, reason for fast warm up, at target in ½ hour was the fan assisted Myson radiator, the matrix is more like a car radiator and so heats up fast as not much water in it, but there is no store of heat, so over night with programmable thermostat set to 17°C the heating would run.

This house not as well insulated, and it can cool over night down stairs to 12°C in the morning I have the TRV heads set in sequence, since all rooms not heated together the rooms do reheat reasonably fast, but again the anti-hysteresis software is too good, and unless I set high then down again it takes as you say 3 hours to heat, but nothing wrong with boiler that's the TRV heads.

One thing we have noticed is pipes heat the floor, so areas of the floor and radiators hold a lot of energy which is slowly released, and heat raises, so if lower floor is heated, middle floor stays warm longer.

Biggest problem is the wall thermostat is too far away from the radiator, so there is a tendency to over shoot, so much depends on last burn of the night, if it has creped up to 21°C it can hold at above 20°C set for a couple of hours, so if we return home at say 7 pm, temperature is on it's way down at 10:30 pm when ready to go to bed, so by 5 am the boiler has kicked in to hold at 17°C, but arrive home an hour earlier, and it has bottomed out at 9:30 pm so at 10:30 pm it is going up, so it can go to 7 am before the boiler kicks in with scheduled temperature change.

The old house is now empty, it normally was warm in ½ hour, but now the fabric is cold, it takes an hour or more.

Since you have EvoHome like with this house the TRV is controlling temperature, so try setting high for an hour then back down, I suspect the boiler has loads of energy to spare, and it is the anti-hysteresis software in the TRV heads which is slowing down the temperature rise.

 

[CBW]

I found mothers house held the better than this one,

Norman Bates is that you?

 

[Rajiv Patel]

I wonder if you have curtains.

The room which appears to suffer the most is the living room. This has a big bay window at one end and French doors at the other so understandably loses a bit of heat. But the windows have plantation shutters and there are thermal curtains at the French doors. The room doesn't feel draughty or uncomfortable when in there - it just seems to drop in temperature faster than expected . Admittedly the drop is not massively different across the different rooms. I have the door closed in the living room.

If you have a timber frame house, or dot and dab plasterboard, the walls will not absorb much heat.

Its brick and block. I suspect its dot and dab plasterboard but not sure.

the radiators might be meanly sized?

I feel like this is the case. The radiators seem quite small for the rooms they are in. This is fine as it's easy to upgrade (provided the boiler can handle it). I'm just more concerned about the heat retention.

The old house is now empty, it normally was warm in ½ hour, but now the fabric is cold, it takes an hour or more.

Since you have EvoHome like with this house the TRV is controlling temperature, so try setting high for an hour then back down, I suspect the boiler has loads of energy to spare, and it is the anti-hysteresis software in the TRV heads which is slowing down the temperature rise.

This is useful to know. I'm not massively worried about the speed at which it heats up - I'm fairly happy with this. It's more the heat loss that's bothering me but may be hard to assess this because i'm not living there permanently yet.

 

[Mottie]

I would think that a mid terrace house like your parents have is always going to retain heat longer than a detached one.

 

[Rajiv Patel]

I would think that a mid terrace house like your parents have is always going to retain heat longer than a detached one.

I was thinking this too. It's entirely possible that the heat loss I'm experiencing is normal for the house given it's size, abundance of windows and the fact I've not lived in it permanently yet. I may have just been spoiled by how well my parents' house retains heat.