Air water pumps

danyosan

Could anyone give me the pro's and cons of this system.

A housing company I have been in touch with has recommended this to me as opposed to solar panels ie. having it connected to an underfloor heating and domestic water supply.

dhaslam

Air to water heat pumps make good sense in this country but perhaps not as the only heating system. For example at this moment the outside temperature is 3.3C which is a bit low but most days the outside temperature would be 5 degrees higher. A good match for the heat pump would be a stove with back boiler, it can be used on cold days to boost heat.

There are a few things to watch out for. First the units are sometimes sold for about ten times their value in this country. Secondly the input and output figuures quoted are probably not reliable. Also the unit needs to be sized properly to run entirely on off peak electricity. There needs to be a good sized heat store in the system to avoid the unit stopping and the output temperature needs to be as low as possible. Water heating is probably not feasible except as partial heat to be boosted by another source.

Compared to ground source air source is much less costly to install and should be almost as efficient in our climate.

I have temporarily installed one but due to a fault I have not been able to measure the efficiency yet. The plan is to use it as the main heating unit in a house I am building. The estimated annual cost at present electricity prices is estimated to be about €300 for a well insulated bungalow of about 225 sq metres. It remains to be seen if the output is sufficient. I am installing a stove and solar panels as well which should reduce the cost further.

danyosan

dhaslam wrote: »

Air to water heat pumps make good sense in this country but perhaps not as the only heating system. For example at this moment the outside temperature is 3.3C which is a bit low but most days the outside temperature would be 5 degrees higher. A good match for the heat pump would be a stove with back boiler, it can be used on cold days to boost heat.

There are a few things to watch out for. First the units are sometimes sold for about ten times their value in this country. Secondly the input and output figuures quoted are probably not reliable. Also the unit needs to be sized properly to run entirely on off peak electricity. There needs to be a good sized heat store in the system to avoid the unit stopping and the output temperature needs to be as low as possible. Water heating is probably not feasible except as partial heat to be boosted by another source.

Compared to ground source air source is much less costly to install and should be almost as efficient in our climate.

I have temporarily installed one but due to a fault I have not been able to measure the efficiency yet. The plan is to use it as the main heating unit in a house I am building. The estimated annual cost at present electricity prices is estimated to be about €300 for a well insulated bungalow of about 225 sq metres. It remains to be seen if the output is sufficient. I am installing a stove and solar panels as well which should reduce the cost further.

I'd be interested to see what your results are.

We are building a low-energy house (U value of walls 0.15) so I was thinking that this would be the only requirement for heating, good to know if I'm wrong.

For the entire system, underfloor heating, air water unit and domestic water heating, supplied and fitted for a 230m2 house, we were quoted 28K. Is this excessive and would it be sufficient as the sole heating system?

dhaslam

28K seems quite a lot for the installation but it does depend on the spec. Underfloor heating seems to be €50-60 per sq metre. The basic materials , 1Km of pipe at €1000 and about €500 each for staples and manifold. However individual controls to each room with wiring back to the distribution position clocks up the cost considerably. What is probably pushiong up the overall cost is the heat pump. I paid £600 for mine but it should be about £1050. A buffer tank is essential with a heat pump because when it stops it takes a long time to start up again. I had thought of not using solar panels becuse the heat pump should work well in summer but I have changed my mind on this. I am also going to install a wood stove with back boiler. If the heat pump is the only heat source a backup immersion would be useful for breakdowns. Air source heat pumps are likely to have more faults because they are outside.

danyosan

dhaslam wrote: »

Air to water heat pumps make good sense in this country but perhaps not as the only heating system. For example at this moment the outside temperature is 3.3C which is a bit low but most days the outside temperature would be 5 degrees higher. A good match for the heat pump would be a stove with back boiler, it can be used on cold days to boost heat.

There are a few things to watch out for. First the units are sometimes sold for about ten times their value in this country. Secondly the input and output figuures quoted are probably not reliable. Also the unit needs to be sized properly to run entirely on off peak electricity. There needs to be a good sized heat store in the system to avoid the unit stopping and the output temperature needs to be as low as possible. Water heating is probably not feasible except as partial heat to be boosted by another source.

Compared to ground source air source is much less costly to install and should be almost as efficient in our climate.

I have temporarily installed one but due to a fault I have not been able to measure the efficiency yet. The plan is to use it as the main heating unit in a house I am building. The estimated annual cost at present electricity prices is estimated to be about €300 for a well insulated bungalow of about 225 sq metres. It remains to be seen if the output is sufficient. I am installing a stove and solar panels as well which should reduce the cost further.

One more thing, how confident are you of the €300 a year running costs? Seems very cheap to be getting heating and hot water out of that.