warm air replacement

[wolfman1]

I would suggest you look at the Worcester Bosch air/air heatpump for the conservatory.

It is not easy extending an existing warm air system in most situations.

The air/air heatpump is at least as economical as a gas wet system for this application and has the ability of providing air cooling in the summer built in.

We have a couple of customers who've had these air/air units installed by us this year and the feedback has been brilliant.

These units must be incredibly efficient, with electricity being several times cost per kwh of gas how is this converted to heat economicaly, efficiently i can understand, economicaly i can't, well now i think about it yes i can, the "heat" comes from the outside air so you get more kw of heat out than you use electrcity in, right? i didn't want the conservatory heated from the main system and was looking at ways to heat quickly when needed rather than try to keep it warm all the time, heat pumps were a way of doing this and the prices are really competetive now B & Q have some really good deals at the moment.

 

[Agile]

These units must be incredibly efficient, with electricity being several times cost per kwh of gas how is this converted to heat economicaly, efficiently i can understand, economicaly i can't,

Air to air or just your house warm air unit are a good way to heat the conservatory as the air is heated quickly but only when you want it.

But the air to air heat pump is not economical in use compared to gas because, although 1 kW of electricity may produce 3-4 kW of heat under ideal conditions, the cost of electricity is now usually about 4-5 times that of gas!

Added to that the capital cost of the air to air is very high compared with any other form of heating and has a very short warrantee.

These conservatories look lovely in the brochures but are not so ideal during the cold weather when they are expensive to heat and not always very good after dark when you may be like illuminated goldfish inside your fish tank when watched by any neighbour overlooking the room!

Tony

 

[simond]

The Bosch units are generally of a better build quality and incorporate the latest inverter driven compressors giving highest efficiency.

In terms of energy costs, gas is around 3.8p per Kwh and electricity is around 13p per Kwh (British Gas have 11.8p per Kwh on their std tariff).

Therefore at a CoP of 4 you are running cheaper than gas. The CoP varies with the load and the external temperature.

Personally I wouldn't buy a heat pump from B&Q. Worcester have a 2yr warranty.

 

[David937]

Is it true that air to air heat pumps can't be used for heating when the outside temperature drops to 5C and below?

 

[Agile]

Its true that they have a likelyhood of icing up when the temperature falls much below zero but that also depends on the humidity.

Luckily the humidity is often very low during cold weather.

Tony

 

[David937]

So you could heat your whole house with air to air heat pumps?

 

[simond]

Simple answer.

Yes.

There are thousands of commercial buildings in the UK that have for years been heated (and more often cooled) by air source heat pumps.

We are not inventing anything new here, all that has happened is the price has come down.

ASHPs have a de-icing programme and many can deliver a performance down to -20C - albeit a much reduced one at this level.

 

[David937]

Thanks for the info, IIRC my Uncle and Aunty who live in Canada have an air source heat pump, there is a single outdoor unit and a large indoor unit in the basement which has return air ducts and supply air ducts. It's used for air conditioning in summer.

 

[wolfman1]

I think i will try the heat pump for the conservatory, the b&q jobies are apparently not that efficient (as reported by one of their competitors!) but they are cheap to buy, I encountered another person running warm air heating on saturday, apart from some issues with the original installation (which led to him thinking about changing to rads) these issues were rectified (new engineer spotted that the up ducts weren't connected) and again he is very happy with the comfort levels and cost of running, well as they say proof of pudding is in the eating, and my new unit is going in next week, i am very eager to try it out once the colder weather appears, having had rads in the past (which never seemed very good) I have my fingers crossed that it will be comfortable and economical, and be capable of heating the house quickly and quietly.

 

[Agile]

But the air to air heat pump is not economical in use compared to gas because, although 1 kW of electricity may produce 3-4 kW of heat under ideal conditions, the cost of electricity is now usually about 4-5 times that of gas!

Tony

A retired bank manager I met in France last month has had no end of problems with his air to air which heats ( or rather usually doesn't ) a large four bedroom bungalow.

Tony

 

[TheMickMan]

Hi Mr Wolfman,

I have a similar problem. I note that your wau is 39 years old, mine is 41 years old, so they may be both from the same manufacturer.

I have lived in this property for nearly 29 years. I remember them being built in 1967, as I delivered all the plasterboard on my lorry.

My unit is a Powell Duffryn (Corrells) model is one of the following, but am not sure which one, GA-25, GA-35 or GA-45. It was orginally a coal gas unit, but modified to natural gas in 1969. Most of these units have been removed in the last 25 years, but I love mine, as it is instant heat when returning from shift work.

I would be very interested to hear more about your wau.

TheMickMan

 

[ColJack]

mom and dad have a warm air central heating and don't have a problem with dust, never have it set above 19 and use less gas than I do to heat my flat with radiators..

 

[wolfman1]

Hi Mr Wolfman,

I have a similar problem. I note that your wau is 39 years old, mine is 41 years old, so they may be both from the same manufacturer.

I have lived in this property for nearly 29 years. I remember them being built in 1967, as I delivered all the plasterboard on my lorry.

My unit is a Powell Duffryn (Corrells) model is one of the following, but am not sure which one, GA-25, GA-35 or GA-45. It was orginally a coal gas unit, but modified to natural gas in 1969. Most of these units have been removed in the last 25 years, but I love mine, as it is instant heat when returning from shift work.

I would be very interested to hear more about your wau.

TheMickMan

What is your similar problem? are you thinking of replacement? My old unit is a Jonson starley JDG50-65, and i am having it replaced with a J&S economaire 65, complete with a water heater and electronic filters.
I have yet to hear from someone who has warm air and doesn't like it.
I sp[oke to a friend yesterday who had warm air heating, he commented that the house went cold quickly when it switched off, but the house was single glazed with no cavity wall insulation and very little in the loft, so i guess it would go cold quickly, his daughter has since bought this house and has fitted rads and they feel this works better, but gas bills are higher?

 

[Agile]

If you are not in the trade then its unlikely that you will ever have significant exposure to people with WAU heating.

For us in the trade we are from time to time asked to work on them and mostly to REMOVE then to be replaced with a wet system.

About 4% of the installations I have been asked to do have been to replace WAU with conventional systems.

Tony

 

[TheMickMan]

Hi, That's very interesting.

I will make a note of the make & model for future use.

Thank you