UPDATED: Air Source Heat Pumps/Air Con - Full Info & Guide, is it cheaper to run than mains gas?

ScottW_3

One dumb question coming up - If I buy indoor units which are designed to heat or cool the air and there is no radiators to heat and it seems that the outdoor unit could not be easily adapted to just heat the water for showers / washing etc, why do I need the outdoor unit as well? Does the outdoor unit heat the air to a certain amount and then the internal units take over to get the air in each room to the desired temperature?

Would I be able to heat my water from the outside unit do you think?

Here are my heating requirements, having used the site recommended by Richard for working out the BTU/Hr for each zone and then converting those to Watts:

Zone1: 3601 Watts
Zone2: 4780 Watts
Zone3: 6345 Watts

I haven't yet gone to the other site to ask for quotes. I would prefer to find out the cost of the units independently of the contractor so that I could judge whether the price they were quoting for installation was a fair price for their labour, or, as is mostly the case, whether they have added a hefty mark-up on the units they buy and then add their labour costs, giving a very high quote.

richardc1983

ScottW wrote: »

One dumb question coming up - If I buy indoor units which are designed to heat or cool the air and there is no radiators to heat and it seems that the outdoor unit could not be easily adapted to just heat the water for showers / washing etc, why do I need the outdoor unit as well? Does the outdoor unit heat the air to a certain amount and then the internal units take over to get the air in each room to the desired temperature?

Would I be able to heat my water from the outside unit do you think?

Here are my heating requirements, having used the site recommended by Richard for working out the BTU/Hr for each zone and then converting those to Watts:

Zone1: 3601 Watts
Zone2: 4780 Watts
Zone3: 6345 Watts

I haven't yet gone to the other site to ask for quotes. I would prefer to find out the cost of the units independently of the contractor so that I could judge whether the price they were quoting for installation was a fair price for their labour, or, as is mostly the case, whether they have added a hefty mark-up on the units they buy and then add their labour costs, giving a very high quote.

Good evening.

To explain the above questions about the outdoor unit... yes you do need this.

YOu need to familiarise yourself with the refrigeration cycle to understand how it works: Not sure if you have read page one but this is copy and paste: Its basically a big fridge turned inside out.

How does it work?

It's actually quite simple. Air conditioners work in much the same way as your refrigerator except there are two separate, but integral, parts to the system. There is an outside unit housing the compressor that is similar to the exterior back of your fridge. It draws warmth from the outside air in even the coldest of weather. That warmth is then transferred inside the home using a refrigerant process through a piping system powered by an indoor fan unit that is typically mounted to the wall. This is why the system is also often referred to as a heat pump rather then air conditioning. Both are in fact the same. Similarly, in summer, the reverse happens. Warm air is drawn from the interior room and expelled by the outside unit.

Heat Pumps are capable of transferring up to 4kW of heat into a space while only consuming 1kW of electrical energy. The energy efficiency of a heat pump will decreases as the temperature difference between inside and outside becomes greater, even at low temperatures a heat pump can provide 3 times as much heat as a normal electric space heater would provide with the same amount of electricity input. This makes Heat pumps extremely energy efficient.

"Not all Heat Pumps are designed to continue working where temperatures fall below freezing point"

The principle of air conditioning always comes down to the same:

absorb energy in one place and release it in another place

The process requires an indoor unit, an outdoor unit and copper piping to connect both. Through the piping the refrigerant flows from one unit to another. It is the refrigerant that absorbs the energy in one unit and releases it in the other.
Cooling mode (Heating mode is the same but in reverse)

1 Indoor unit
A fan blows the hot indoor air over a heat exchanging coil through which cold refrigerant flows. The cold refrigerant absorbs the heat from the air and cooled air is blown into the room.
2 Copper piping
The refrigerant circulates through the units and the piping and takes the heat from the indoor unit to the outdoor unit.
3 Outdoor unit
Through compression, the refrigerant gas is heated and its boiling point increases. In the outdoor unit the obtained heat throught compression is released to the outdoor air by means of a fan which blows the outdoor air over a heat exchanging coil.
4 Refrigerant
The liquid refrigerant flows back to the indoor unit.
5 Indoor unit
Back in the indoor unit, the refrigerant is decompressed and thus enabled to extract heat form the indoor air.

---

Now you have got your load calcs later on I will find you some prices online so you can see what size units you need.

richardc1983

ScottW wrote: »

Here are my heating requirements, having used the site recommended by Richard for working out the BTU/Hr for each zone and then converting those to Watts:

Zone1: 3601 Watts
Zone2: 4780 Watts
Zone3: 6345 Watts

.

Going to see if theres a better calculator as this may have taken into account the flow temp of a radiator you see.

Heres some rough ideas of prices for the indoor units... not sure of price for outdoor unless you ring that company listed in the link below.

Zone 1 - http://www.lgcomfortcooling.com/products4.asp?documentID=108&catAID=3&catBID=58&catCID=134 £298.00

Zone 2 - http://www.lgcomfortcooling.com/products4.asp?documentID=109&catAID=3&catBID=58&catCID=134 £318.00

Zone 3 - http://www.lgcomfortcooling.com/products4.asp?documentID=111&catAID=3&catBID=58&catCID=134 £491.00

Other manfucturers who produce more high end equipment, indoor units will be similar prices but outdoor units will fluctuate but so it may be another 1 or 2k on top of the price.

Ok LG's system might be suitable and this will heat the water and it allows you to use fan coil units.

http://mylg.co.uk/data%20for%20site/therma%20V%20databook%20%28AWHP%29.pdf - 16kw unit then you have a little extra duty should you need it. Page 15 details how the system will connect up with fan coil units, however you will be using ducted but the pictures show floor standing units for demonstration purposes.

http://www.lgcomfortcooling.com/environment.asp?menuItem=5 - ring these for price... cheapest you will find.

My system is LG and it works very well even when it was -10 outside the house was toasty warm.

ScottW_3

Hiya Richard,

Many thanks for your very useful reply. I had actually looked at the first page on this topic and thought I had understood it okay; I understood how the system worked with radiators but I had a misconception of how the fan coil units worked with relation to the outside heat pump - I thought that the outside unit heat exchanger would transfer its heat to air which would then be passed to the indoor fan coil unit for circulation, but now after studying this I can see that the outside air temperature is always transferred to water within copper piping and that copper piping goes to the fan coil unit which blasts air across the heat exchanger and into the ducting which then can come out anywhere that is required.

That has really managed to crystallize my thoughts. The LG system actually looks very impressive to me and it's very interesting to see all the calculations involved in working out the required amount of heating; this reinforces my thoughts that this is not a DIY job and it is necessary to use a skilled engineer for the installation.

So now I need to find out the price of the external unit, the Hydro Kit, the boiler, and the box for all the required settings etc. Anything else apart from the installation costs?

Many thanks again for your help.

richardc1983

ScottW wrote: »

Hiya Richard,

Many thanks for your very useful reply. I had actually looked at the first page on this topic and thought I had understood it okay; I understood how the system worked with radiators but I had a misconception of how the fan coil units worked with relation to the outside heat pump - I thought that the outside unit heat exchanger would transfer its heat to air which would then be passed to the indoor fan coil unit for circulation, but now after studying this I can see that the outside air temperature is always transferred to water within copper piping and that copper piping goes to the fan coil unit which blasts air across the heat exchanger and into the ducting which then can come out anywhere that is required.

That has really managed to crystallize my thoughts. The LG system actually looks very impressive to me and it's very interesting to see all the calculations involved in working out the required amount of heating; this reinforces my thoughts that this is not a DIY job and it is necessary to use a skilled engineer for the installation.

So now I need to find out the price of the external unit, the Hydro Kit, the boiler, and the box for all the required settings etc. Anything else apart from the installation costs?

Many thanks again for your help.

Not really the engineer would quote for the copper piping and insulation.

If you was to have a standard air con system installed one that didnt heat the water, you wouldnt have any of the hydro box, boiler etc you would just have the indoor units and outdoor unit linked by copper piping but instead of water flowing through the piping it would be refrigerant as the heating medium.

Give LG comfort cooling a call and see what price they can do.

I have PM'd you my name mention my name as im a regular customer of theirs and see what they can do

Other systems that heat the water also are:

http://www.altherma.co.uk/default.jsp- Daikins Altherma

http://ecodanlive.mitsubishielectric.co.uk/homeowner/ms_homeowner.asp - Mitsubishi Electrics Ecodan

Not sure if sanyo are also have a system.

ScottW_3

Hi Richard,

I tried to post a reply last night but for some reason Firefox kept coming back with an error every time I tried to send the message; hope it works okay today.

I found that the Altherma link didn't work at all and the Mitsubishi link only had a page with very little on it, so maybe Firefox was playing up here too. Nope, just tried them again and it's just the same as yesterday.

That's an interesting thought to not go for the hydro box and boiler, it would certainly save quite a bit on the initial costs and then keep our immersion heater for the hot water. Any idea how much the immersion heater is likely to cost to keep us in hot water??

Cheers

richardc1983

ScottW wrote: »

Hi Richard,

I tried to post a reply last night but for some reason Firefox kept coming back with an error every time I tried to send the message; hope it works okay today.

I found that the Altherma link didn't work at all and the Mitsubishi link only had a page with very little on it, so maybe Firefox was playing up here too. Nope, just tried them again and it's just the same as yesterday.

That's an interesting thought to not go for the hydro box and boiler, it would certainly save quite a bit on the initial costs and then keep our immersion heater for the hot water. Any idea how much the immersion heater is likely to cost to keep us in hot water??

Cheers

Good morning

I have updated the links above, I think they had expired but they are now working...

Your immersion heater I am not sure how much this would cost the only way you could tell would be to trial it by using it for a week and when operating see how many units it is using.

ScottW_3

Cheers, links are now working fine.

rhubarbe

I said that I would come back and report my meter readings.

Since we had the ASHP installed in April we have loads of hot water, so we can have a bath again, and the washing machine doesn't have to heat the hot water that the combi boiler didn't provide. The ASHP comes on to heat water at 5:00am and switches off, job done, at about twenty five past. This gives us 150L of hot water that usually lasts us all day.

We have not had to use the heating much but we are happy that the use of this isn't exorbitant (I appreciate that it is Summer).

Last Summer (pre-ASHP) we were using about 60-70 units electricity a week and about £5 a week in LPG.

This year we are using about 70 units electricity a week and no LPG.

I call that a result.

I will update as we start to use heating as the weather gets colder.

It's also quieter; breaks the ice at parties and saves us having to go down the oil route.

On a very hot day you can switch it on to hot water only and go and sit outside in front of the fan (which blows ice cold air) - bliss!

I'd recommend one.

Cardew

https://forums.moneysavingexpert.com/discussion/2610437

Not a happy camper!!