Heating with electric rads and no gas boiler for now

JayBee66 · 06-11-2023 07:08AM

I performed successive overnight experiments on a bedroom to see the difference between a €400 2000W ceramic core electric radiator and a cheap €64 500W convector heater. The bedroom has a floor area of 16.5 m^2 with two exterior walls and one of the other two internal walls adjoining an unused bedroom that is never heated and is the coldest room in the house.

The bedroom being heated had a starting temperature of 14.5C and a target temperature of 16C.

As expected, both devices required the same amount of power to run them during the night . Both devices being as good as 100% efficient, heat loss from the bedroom demanded that the convector heater was switched on 4 times as much as the ceramic core heater (i.e. 2000W/500W = 4).

The only difference between the two devices is aesthetic. The ceramic core radiator is near silent with a slight whine when drawing power (inaudible if on the other side of the room). The convector makes a single click on and off with some "creaking" when warming up and cooling down. If sound annoyance whilst trying to fall asleep is important to you then there will be an upfront cost of €336.

Conclusion - If your only metric is hardware cost then buying cheap is the best option. Noise issues add a significant upfront cost.

DC999 · 06-11-2023 09:33AM

Yeah, as you say there is no difference (bar cosmetic) on the more expensive ones. Our 5x5m sitting room is heated with a 700w heater on a thermostat, using ~5kWh a day in total. It stays at 19C until bed time, which is a good temp for us. Cost me €20 when I bought on donedeal in the summer (when no one wants heaters). Was less than 1 year old when I bought it. Oil filled electric rad.

And I've a 400w heater in the WFT room downstairs. Again, on a thermostat. That's all our heating at the moment for the whole (small) house.

denismc · 06-11-2023 09:51AM

This is an interesting thread.

Can I ask what DCV you used?

We replaced our windows a few years ago and the new ones have no trickle vents so currently our ventilation system consists of me opening windows depending on which way the wind blows.

Also re: the insulated wallpaper, will BER assessors consider this as an improvement when they do their calculations?

DC999 · 06-11-2023 01:31PM

https://www.boards.ie/discussion/comment/121331069#Comment_121331069

I've no DCV (Demand-Controlled Ventilation) bar windows and unexpected air holes :) It's an old, leaky house that the wind passes through so there are more air changes than I'd like. So air quality isn't an issue.

I've a dehumidifer running as a heater in one small room. But that only removes moisture of course, it's not cleaning the air.

denismc · 06-11-2023 02:31PM

https://www.boards.ie/discussion/comment/121332142#Comment_121332142

Sorry my question was aimed at @JayBee66

JayBee66 · 06-11-2023 05:55PM

https://www.boards.ie/discussion/comment/121331069#Comment_121331069

We got our DCV direct from Aereco in Cork. I think there is another manufacturer but I forget the name. We need DCV as being amongst farming land, opening windows between the end of July and early April will result in a messy cluster fly infestation.

To get DCV from Aereco, they need a floor plan and they tell you what you need. After payment, you'll get a pallet with everything on it. Installing the wall vents (make sure to get the new ones that also come with sound baffles and insect proof screens) is easily done through existing 110mm vents or new 100mm holes need to be drilled in walls without vents.

I haven't installed the wet room extractors yet. I'll do that in the spring. Even though there are no extractors there is enough throughput of air with vents at either end of the house to keep the air fresh. The house is not noticeably colder compared to last year, when the old vents were blocked with rags. Putting your hands up to the sides of the vent, you don't feel a lot of air rushing in, even on a windy day. There are flaps in the vent tubes, which close up if the wind is high.

A BER assessor might consider insulated wallpaper, if you want them to. The Wallrock Thermal paper available at Screwfix has a U value of 12.19 W/m^2K so there is something for them to factor into their equations; especially heat loss calculations when applying for a heat pump grant.

graememk · 06-11-2023 06:10PM

https://www.boards.ie/discussion/comment/121333585#Comment_121333585

Isn't that u value really high? A solid block wall u value is something like 2w/m²K.

62.5mm(50mm insulation, 12.5mm plasterboard)of insulated plasterboard has a u value of 0.3

To have any effect? Wouldn't the u value need to be lower?

Edit: To calculate u value of a combined wall, you add all the R values of each component, an divide 1 by that value

Eg 1/ (R1 +R2.. etc)

I suppose to get the r value from a U value you divide 1 by the U value again.

Edit 2:

Done more math

Solid wall, u value of 2 r value of 0.5

Insulated wallpaper, r value of 0.05

Total r value = 0.55

1/0.55 = new u value of 1.81,

If used insulated plasterboard (wall u value, 2, insulation 0.3)

New total U value is 0.26.

(Only figuring this out on the fly here so open to correction)

JayBee66 · 06-11-2023 06:23PM

https://www.boards.ie/discussion/comment/121333645#Comment_121333645

I guess that it's better than paint or standard wall paper. This page - https://www.anaglypta.co.uk/our-papers/style/foundations/item/wallrock-thermal-liner-kv600 - claims that the addition of Wallrock lowers a wall's U value to 1.79W/m^2K

Well, it's worth a try. I have a thermal imaging camera. We'll see the difference.

graememk · 06-11-2023 07:13PM

https://www.boards.ie/discussion/comment/121333695#Comment_121333695

That 1.79 isn't far off my edit of 1.81! So I must be on track.

It's a lot less inconvenience than replasterboarding a wall

Heating with electric rads and no gas boiler for now

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