Heating with electric rads and no gas boiler for now

JayBee66

We use desiccant dehumidifiers to heat the house at this time of year. They remove the damp and have a small heater in them to liberate the water from the desiccant so it flows into collection tank. The heater warms the room better than a compressor dehumidifier and is quieter.

Humidity is what makes you feel colder in winter and muggy in summer. Ireland being well-known for its dampness, all year round. We might raise the temperature of the house by two degrees in summer but don't feel it because the humidity is lower. In winter, we keep the door of the room in use closed and run a dehumidifier. Warms the room to about 19C and reduces the humidity to about 45% from about 65%. 19C with 65% humidity would feel colder than 19C with 45% humidity.

We only heat rooms in use and aim to keep the rest of the house above 16C, which is fine for bedrooms.

There's a wood heater in the living room for persistent sub-zero nights and a fanless ceramic core radiator that I mounted on a wooden frame to make it portable for use around the house. The ceramic radiator might be used in the office or herself's snore-free bedroom. I'm happy in a colder bedroom so long as it's been dehumidified to take the damp feel off the duvet.

Our 5KW battery is more than capable of running a dehumidifier during the evening before being recharged at 11PM with cheap rate electricity.

I might import a cheap 1200W infra-red panel from the UK. I'm not paying the extortionate amount that pushy fella wants. I'd use the panel to irradiate an internal wall with excess power during the day so it re-radiates during the evening. Home Assistant will monitor export rather than an Eddi. The money for which will buy some heaters.

DC999

https://www.boards.ie/discussion/comment/121246719#Comment_121246719

Class, I'll try the same with my dehumidifier. If it makes the room warmer, that's a huge win. I've a compressor one and have it on a thick rubber matt to dampen the sound. Too noisy vibration-wise otherwise. Plus it puts out 30c+ heat (ok, from a very small space but it does actually generate heat while removing water) - win, win.

I point my WFH infrared heater to the wall and it bounces back at me. Too warm when facing it directly. And it then radiates heat back into the room - so it's not lost as you say.

unkel

Compressor dehumidifier has a COP of around 1.4 too, so you'll save a bit of electricity there 😁

JayBee66

https://www.boards.ie/discussion/comment/121247257#Comment_121247257

As @unkel says, there's a bit of COP with a compressor dehumidifier but for some reason the heating is better with desiccant dehumidifiers. I can see with my IR camera that the compressor has a hotter core than the desiccant but it doesn't get out into the room as quickly. The heat from the desiccant's PTC heating element gets blown straight through the desiccant and out into the room. Whereas, the heat in the compressor pump tends to stay trapped in the compressor and takes longer to get out thus allowing time for the room to cool. The air coming out of the desiccant dehumidifier always feels warmer.

Possibly, it takes time to build up the higher temperature in the compressor and if it was vented constantly then the running temperature would be lower than the desiccant. Also, the desiccant is getting additional energy input so will always generate more heat though not as efficiently.

I have one compressor and two desiccant dehumidifiers. The compressor's role is always damp removal. I leave the other two where there is need for heat too but it's only ever COP ~1. Still, the heat is free and the equipment doesn't cost anything like that of a heat pump.

Today, the house core temperature is about 17C but the living room was at 19C thanks to dehumidification. I watched Only Connect in t-shirt and shorts. The compressor was in herself's bedroom, sucking it dry but only keeping the room at 17C. Fine for sleeping. There is a Demand Controlled Vent in that bedroom, which I installed this summer. I'll report on its effectiveness in spring but it's already made a difference with air freshness.

That's the first cold snap dealt with. It's going to get a little warmer at night for a while. We'll see what the longer cold snaps have in store this winter. Ideally, I just want to put in one charge of wood in the stove each evening, when the time comes, as opening the stove door to refuel it is bad for my respiratory system and that puts me back on the antihistamines. I might buy some fanless 500W heaters and when the humidity is below 50%, get Home Assistant turn off the dehumidifier and run a fanless heater (which will have more power than the desiccant PTC heater and will raise the room temperature closer to 20C - herself's comfort zone) until the humidity creeps back over 60%

SharkMX

https://www.boards.ie/discussion/comment/121115036#Comment_121115036

Ive seen a few fan heaters and convection heaters go on fire over the years. Also saw an oil filled heater start smoking heavily once. I think it was probably left on its side at some point. They need to always be upright.

But at least with the oil filled rads its much rarer to have a fire and not as susceptible as fan heaters or convection heaters to have fluff blow into them or something left on them or fall in front of them. I would never leave any heater other than an oil filled one unattended.

DC999

https://www.boards.ie/discussion/comment/121248908#Comment_121248908

+1 to that “I would never leave any heater other than an oil filled one unattended.” But I’d add where there is an open heating element. I’d leave an infrared heater on unattended as there are no moving parts (granted it’s useless when there is no one in front of it to heat). I'd be very conscious of the potential for fire.

I’ve our electric rads on a separate thermometer plug. So when the room gets above the set temp, it turns off the plug on the rad. Meaning there is another safety ‘check’ in place there. The oil rads are supposed to turn off when on their side, but that’s down to a sensor which might not work – so I wouldn’t trust it. And they have a thermostat on them and are supposed to cut out when they reach that temp. Again, I wouldn’t trust it for something that is on even at night when we're in bed. Not on something that costs maybe only €50.

JayBee66

I bought a Glen 2150 500W heater. Can be had from Screwfix for €64 or £52 from Amazon. Runs in a bedroom at the north end of the bungalow on night rate electricity, paid for with credit from the summer's feed in (3200KWh!). The heater is put on a low setting to keep the room at just over 16C. I'd say it uses about 2-2.5KWh of power during the 7 hours it's on for.

Unless the price of heat pumps falls dramatically, I can't see us getting one. Yes, it may (depending on weather and quality of installation) produce 4 times the heat for the same energy input as the convector heater above but the up front cost is a turn off. I don't like the idea of installers/manufacturers gouging our savings. They are going to want to replace our paper thin, single wall radiators and maybe add a few as well.

I deliberately avoided a "one-stop" approach to our renewable retro-fit so that I could evaluate each change made. First was the aluminium-clad wood framed triple glazing, which was half the price I was expecting. No more draughts. No more condensation.

Next were the desiccant dehumidifiers, needed after the draughts were removed. They also generate a little heat, keeping the house dry and about 16C. This resulted in a need for cheap electricity and so the PV went in. After a year of teething problems (which I solved rather than the installers) the PV is now working perfectly and integrated with Home Assistant.

I then decided to unblock those vents I had closed off because the air was being replaced far too quickly and making the house cold. After being quoted €8000+ for Mechanical Heat Recovery Ventilation, I went for €2300 of Demand Controlled Ventilation delivered on a pallet. I installed the wall vents and already the air is fresher but not cold. A gentle trickle comes through the controlled vents and the sound baffles do a great job. I'll install the wet room extractors in the spring when the cluster flies leave the attic.

A wood stove is used in the living room at night, charged with one load of twigs and logeens from the river. I used to make briquettes from wood shavings and newspaper but my back doesn't like working the press so I'll have to automate the press with a car jack and motor. The briquettes are great but need a high wood content (50% plus) to maximise heat, length of burn and minimise ash.

The house was built the old fashioned way (locally built by a relative of a relative of a relative) and for a 21st century house there is terrible heat bridging at the top of the insulated cavity wall. I shall experiment with the bedroom at the north end and cover the walls with Wallrock fibre insulated wallpaper. About 4mm thick. An independent painter and decorator on YouTube has it in his house and loves it so worth a try. If it slows down heat loss and we use less electricity to heat the room then that'll be great.

The aim has been to heat, power and air condition the house cheaply but effectively and so far so good. The house had a BER of C3 and when last evaluated was B1 but is probably into the As now.

unkel

Totally agree with your attitude, @JayBee66. There are heatpumps and heatpumps though. Personally I have no desire to spend the guts of €10k on an air to water install, even if there is a decent subsidy on it. I will likely go air to water with a couple of split units, total cost roughly the same as a gas boiler replacement, no subsidy on this though and use cheap electric COP 1 heating in the rest of the house and my large garden room / office

Currently I use half electric heating, half gas. Herself likes a few hours of the gas fire on in the living room (coldest room in the house) in the evening. Gas central heating is used sparingly, we never have radiators in bedrooms on

One thing I don't understand from your post (probably because I'm a bit thick and not good at things mechanical) is:

"I then decided to unblock those vents I had closed off because the air was being replaced far too quickly" - how can the air be replaced quickly when the vents are closed off?

JayBee66

https://www.boards.ie/discussion/comment/121289630#Comment_121289630

I had blocked the original vents because the air was being replaced too quickly. The warped PVC frames had effectively replaced the vents so the vents were no longer needed and blocked with old tea towels. After replacing the windows, the house had become too airtight and so in went the DCV. I fed the 100mm DCV tubes through the 110mm tubes of the former vents along with a squirt of expanding foam.

DC999

https://www.boards.ie/discussion/comment/121289573#Comment_121289573

Good write up, cheers.

I have PV but a lot of other stuff to sort in an old cold house. Like you, will be as diy as I can do. Won't be one stop shop for sure.

JayBee66

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

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

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

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

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

Sorry my question was aimed at @JayBee66

JayBee66

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

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

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

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