Aquair warm air system

danrv

Hi
I have 1970’s electric warm air heating in my three bed semi detached property, that I’m looking to update. I’ve posted a few times here regarding electric heating options which are limited to storage heaters or electric rads.
The radiators could be expensive to run although they won’t all on at the same time. 
What I’ve been looking for is something to replace the Unidare 10kw storage heater but use the in-wall ducting. I’ve seen this 
Aquair system from Electric Heating Company that claims to be a replacement for systems like mine.
Not sure if this would be less economical as it doesn’t use a hot water storage system as a heat source.
https://www.electric-heatingcompany.co.uk/electric-boilers/warmair-heating-replacement/
Any help appreciated.

Gerry1

You'll get more answers in the Energy forum: this one is for LPG, Heating Oil, Solid & Other Fuels.

But the answers will still tell you the same thing.  Regardless of whether it's a Magic Dust radiator, or a glorified built-in fan heater system, you'll be paying sky high daytime rates and virtually nothing else will be more expensive.

matelodave

As far as I can tell it's a hot water heat exchanger coupled to a hot water tank. Hot water is pumped through the exchanger and then blown out through the ducting.
As Gerry says, there really cant be many other systems that would as expensive to run as you'll be using full price leccy to keep the water hot hot so it can be circulated.

I'm guessing that the ElectricAir system that you have is based on storage heater technology which uses off-peak electricity to store enough energy to circulate during the day. You cant store enough hot water in a tank to do that (well you can - but it has to be an exceeding large tank) so you cannot get a great deal of benefit from an off-peak supply.

danrv

Gerry1 said:

You'll get more answers in the Energy forum: this one is for LPG, Heating Oil, Solid & Other Fuels.

But the answers will still tell you the same thing.  Regardless of whether it's a Magic Dust radiator, or a glorified built-in fan heater system, you'll be paying sky high daytime rates and virtually nothing else will be more expensive.

Yes, keep forgetting about the correct forum. 
Guess I'll need to wait for a revolutionary new electric heat invention.

Gerry1

danrv said:

Guess I'll need to wait for a revolutionary new electric heat invention.

Won't do you any good unless it comes with lifetime electricity at 2p/kWh.

The nearest you'll get is a weird and wonderful heatpump that's expensive to buy/install and is still far more expensive than gas to run.

danrv

matelodave said:

As far as I can tell it's a hot water heat exchanger coupled to a hot water tank. Hot water is pumped through the exchanger and then blown out through the ducting.
As Gerry says, there really cant be many other systems that would as expensive to run as you'll be using full price leccy to keep the water hot hot so it can be circulated.

I'm guessing that the ElectricAir system that you have is based on storage heater technology which uses off-peak electricity to store enough energy to circulate during the day. You cant store enough hot water in a tank to do that (well you can - but it has to be an exceeding large tank) so you cannot get a great deal of benefit from an off-peak supply.

Yes, it's a huge 10kw storage heater that charges on E10 cheap rate.
Most old warm air systems tend to be gas but this is electric. House this size
really needs gas or oil CH.
I was getting my hopes up after spotting the Aquair electric warm air system. 
Then realized it doesn't use stored water. 
I guess my immersion tank wouldn't work with it. That gets really hot after an hour.

Gerry1

danrv said:

Yes, it's a huge 10kw storage heater that charges on E10 cheap rate.

You might be better off with Economy 7 if it's big enough not to go cold in the late afternoon and evening if it doesn't get those E10 daytime boosts, and you'd get a wider choice of suppliers and tariffs.

matelodave

An Electricaire R10 (10kw) is designed to store 73kwh of heat (10kwh for 7 hours using off-peak leccy) and then deliver that heat as required over approx 17 hours at round 4kwh. If you use an e10 supply then you could possibly be storing up to 100kwh a day and delivering it over 14 hours at approx 7kwh

You need a hot water tank of around 1000litres capacity to store that amount of energy (see the example below). Bearing in mind that the average domestic hot water tank is around 150-200litres you can see that you'd need a rather large thermal store (about 6'6high by 2'6 in diameter) with a 10kw immersion heater to be able to store the same amount of heat and use it in the same way as your Electricaire system.

Example - Energy stored in a 1000 liter water tank

Water is heated to 90oC. The surrounding temperature (where the energy can be transferred to) is 20oC.

The energy stored in the water tank can be calculated as

E = (4.2 kJ/kgoC) ((90 oC) - (20 oC)) (1000 liter) (1 kg/liter)

    = 294000 kJ

    = (294000 kWs) (1/3600 h/s)

    = 81.7 kWh    

• 1 J (Joule) = 0,1020 kpm = 2.778x10-7 kWh = 2.389x10-4 kcal = 0.7376 ft lbf = 1 (kg m2)/s2 = 1 watt second = 1 Nm = 1 ft lb = 9.478x10-4 Btu
• 1 Btu (British thermal unit) = 1055.06 J = 107.6 kpm = 2.92875x10-4 kWh = 251.996 calorie (IT - International Table calorie) = 0.252 kcal = 777.649

Gerry1

Not quite...

An Electricaire R10 (10kw) is designed to store 73kwh of heat (10kw for 7 hours using off-peak leccy) and then deliver that heat as required over approx 17 hours at round 4kw. If you use an e10 supply then you could possibly be storing up to 100kwh a day and delivering it over 14 hours at approx 7kw.

FTFY ! 

danrv

Gerry1 said:

You might be better off with Economy 7 if it's big enough not to go cold in the late afternoon and evening if it doesn't get those E10 daytime boosts, and you'd get a wider choice of suppliers and tariffs.

Thanks. Yes did consider E7 for more tariff choices. My Economy 10 cheap rate is in one chunk.
Originally 10.00pm - 8.00am although this has now become 5.10am - 3.10pm due to BST shifts over the years.
Maybe it’s in one chunk as it’s a large warm air heater and not individual space heaters. 
The cheap rate time shift actually works ok as it keeps the heater warm later in the day.
With E7 I think it’s set at 12.00 - 7.00am. Not sure if there’s any flexibility on these times.
There’s no modern equivalent available so would have to go with Quantum space heaters on E7 for electric heating.