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Heating Settings

Posted by daiking , 02 November 2015 · 902 views

I’m looking for something qualitative rather than quantitative whilst I'm musing to myself, comments will usually trigger something in my mind to make a bit of sense and give me something to work on.

Having previously spent a long time in a house that was impossible to comfortably warm and before that a flat with E7 heating, I’ve got no feel for what settings I should be aiming at rather than just going with whatever is comfortable. Add to that we moved into this house in April and have since torn it apart, I’ve not even got a baseline of how the place feels or what it costs to run – We had a new Baxi combi boiler and radiators put in with a Honeywell wireless controller. So far this autumn, we’ve not had the heating on (Except for an electric blanket) and it has been chilly at times but we’ve managed. There are so many holes in the fabric of the house at the moment I didn’t see much point in trying to heat it unless absolutely necessary.

As a test, I put the heating on yesterday for about 10 minutes, with downstairs rads TRV on a mid-setting, they warmed up quickly and were very warm to the touch, bolier water temp set to 60 degC. Switched it off after 5-10 mins and let things settle again. The controller indicated an ambient temperature of 18.5 deg in the back of the house (East) – weather yesterday was foggy and overcast. At about 4pm the controller settled at 18.5 degC so I lowered the thermostat to 16 degC and left it on for the rest of the day. By the time we went to bed at about 11pm the thermostat displayed 16.5 degC and the heating had not triggered since I set it. I switched the heating off as I didn’t want it to come on in the night.

At 7am this morning, the thermostat was showing 14.5 degC and the outside temp, according to my car was 7 degC. I think that once we complete our extension I’m going to have to increase the comfort level somewhat and ultimately that will come down to some guesswork and trial and error but what’s a good place to start? Plus there’s a unknown dynamic in how we use our new open plan area hopefully with UFH. The other rads might not be needed as much if we spend most time in there or we might need rads in here if the UFH is not strong enough.

I had no input into the current radiator sizes (not that I could) although I was assured they were ‘over-size’. If I go round and take some basic measurements, will someone help me work out a very basic model on what sort of water temp I’m looking at and the performance I can expect? I’d only be looking for something broadly accurate rather than pointlessly precise.

We had originally planned on getting a WBS to give us ‘top-up’ heating but it makes no economic sense even when you’ve 3 tonne of wood stacked in the garden. Instead we’re getting a gas fire in our small lounge. The saving (£1000+) buys a lot of gas for a room we can reasonably turn the heat up on when we need it and leave the rest of the house at a lower temp.

At the risk of taking this blog off at a tangent before I even finish it, despite the lack of heating so far, the house is no colder than the terrace house we previously rented with solid wall and single glazed windows AND the heating on.

this is the first time I've ever paid much attention to this. Monday and tuesday were colder days, with outside temps struggling to get into double figures in the daytime but not going much lower in the night. Hence the house has been falling 2 degrees colder in the evening down to 14.5 degree but still being at 14 degrees in the morning with a 6-7 degree outside temp.

Strangely today though my told me it was 11 degree this morning but the heating thermostat was showing 14degrees inside which is a little lower than I would have expected. If temps stay higher today, I expect the house will settle at a lower temp tonight and first thing tomorrow evening.

Surprising how much difference that 2 degree evening temp difference makes. On sunday I managed in a T-shirt but the past 2 nights has felt really chilly and needed an extra layer and then some. Sat under a duvet on the sofa watching tv.
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In still air, you lose far more body heat through radiation than convection, so the delta between the surface temperature of your clothes and the 6 walls / floor / ceiling is more important than the spot air temperature itself. The rough figure is 7W/mK. Wearing a warm pullover not only insulates you, it drops your outer surface temperature and drops your radiant losses as well.

The main convection losses are from your head, so that's why Victorians wore a hat and an outer dressing gown or smoking jacket.
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Precisely, although i couldn't have put it that way.

But if I'd been asked to quantify what sort of temp difference takes you from ok to chilly, I'd guess 5 or 6 degrees not an indicated 2 - especially because of the clothing benefit. I should get a thermometer rather than relying on the CH wireless Stat and see how things go.
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Having warm walls makes a big difference. A cosy temperature in the summer is often quite a bit less than in the winter for this reason. We're building a near passive house so all of the inner fabric is essentially within ½°C of the room temperature. In an older house dry lining the walls with 25 or better 50mm PUR backed plasterboard can make a hug difference -- even if it's only in a snug room that you mainly live in in the winter months. If you do that then you can tolerate a lower base temperature in the rest of the house.
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Had a pleasant surprise. Although we're not fully done yet and this winter has not been a cold one, combined gas/Elec bill was around £100 a month.

Having spent 4 years in house where the bills rose to £140 per month and was still freezing I'm very happy although I appreciate its not exactly low energy at £100 per month. I'll take a look at the spilt and see where we go next. To my shame I've not even finished re- insulating the old loft let alone the new one. What's possible next winter? 20% saving?

My wife happened to meet the new tenants of the place we rented and despite the landlord tarting up the kitchen and the bathroom there has been no change to the fabric of the house and the 40 year old boiler. They said it was freezing cold too so not our imagination. It's a shameful state of affairs and more should be done to force landlords to bring their properties up to scratch.

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