Air source heat pumps

[beeker]

Same here, learning lots from this. Still no wiser though on the best way to go.

I'm looking to the future, and would like some unbiased advice from someone, rather than a salesman, who all seem a bit snake oily on this.
I live in a converted fairly open plan barn, EPC is D, with an LPG boiler and wet underfloor heating, plus a log burner, all were installed on conversion in 2006, got a few pitched roofs facing wsw, and obviously the other side ese, and one small facing due south, which may not be useable due to planning, so looking to explore all the options. Solar, battery etc, two cars, open to EV as both commute about 30 miles round trip 3 times a week, plus mainly local with the odd road trip. No mortgage, nothing on finance etc. Both getting nearer to retirement age, though we won't

 

[Penninetrader]

Same here, learning lots from this. Still no wiser though on the best way to go.

I'm looking to the future, and would like some unbiased advice from someone, rather than a salesman, who all seem a bit snake oily on this.
I live in a converted fairly open plan barn, EPC is D, with an LPG boiler and wet underfloor heating, plus a log burner, all were installed on conversion in 2006, got a few pitched roofs facing wsw, and obviously the other side ese, and one small facing due south, which may not be useable due to planning, so looking to explore all the options. Solar, battery etc, two cars, open to EV as both commute about 30 miles round trip 3 times a week, plus mainly local with the odd road trip. No mortgage, nothing on finance etc. Both getting nearer to retirement age, though we won't

The log burner, do you provide an outside combustion air source for it ? If not that is a good place to start. Like myself you have I think lots of questions needed answering before making a pragmatic decision.If there is suitable land around the barn would ground source not be able to play a part. On the LPG, when mains gas rose up to 300% in price to the consumer during the crazy time, LPG even in 47kg bottles rose by about 25%, making it cheaper for a time than mains gas. When govs play games it is difficult to make long term decisions due to their changing the rules of the game at a whim. If you come up with anything let us know. Retire, not happening here either

 

[Gilberdyke John]

Does anyone make hybrid systems where the heat pump for example preheats water entering a gas boiler?

One of my neighbours had wet solar roof panels installed. The solar heated an unvented hot water cylinder which fed into the cold inlet of their modulating gas combi. When the water was hot the combi didn't fire up but at lower temperatures the flame came on and added sufficient heat to output the desired temperature to the taps. That part of the system worked fine but the installers had fitted an automatic air vent on the very top of the system (the apex of the roof so inaccessible). Whenever the temperature in the panel rose above around 60 degrees C the heat transfer pump was inhibited to avoid scalding. The temperature in the panel rose and the water vapourise (boiled). The automatic air vent float dropped in its chamber, the vapour was evacuated and when the sun went off the panels they cooled down but the system pressure had gone. Thus the heat transfer pump remained inhibited and the installers came all the way from miles away to recharge the system. This usually took some days so their investment was off line more than it was on during sunny times of year. They had tied themselves into a service agreement for good measure. I studied their system prior to installing my own (with modification) and did explain the problem to my neighbours but the installers wouldn't admit they were at fault. The saga rumbled on...........

 

[Penninetrader]

One of my neighbours had wet solar roof panels installed. The solar heated an unvented hot water cylinder which fed into the cold inlet of their modulating gas combi. When the water was hot the combi didn't fire up but at lower temperatures the flame came on and added sufficient heat to output the desired temperature to the taps. That part of the system worked fine but the installers had fitted an automatic air vent on the very top of the system (the apex of the roof so inaccessible). Whenever the temperature in the panel rose above around 60 degrees C the heat transfer pump was inhibited to avoid scalding. The temperature in the panel rose and the water vapourise (boiled). The automatic air vent float dropped in its chamber, the vapour was evacuated and when the sun went off the panels they cooled down but the system pressure had gone. Thus the heat transfer pump remained inhibited and the installers came all the way from miles away to recharge the system. This usually took some days so their investment was off line more than it was on during sunny times of year. They had tied themselves into a service agreement for good measure. I studied their system prior to installing my own (with modification) and did explain the problem to my neighbours but the installers wouldn't admit they were at fault. The saga rumbled on...........

This is the thinking of my Nephew who has a great deal of knowledge in these matters, that is preheating in some form or other. I have made the case, both to him and my son, that an all or nothing approach is simply the wrong route to take. My Nephew is credentialed in gas, lpg, oil and heat pump.

 

[jenkinsbrynmair]

My Nephew is credentialed

sounds painful

 

[Peterjay]

In that regard the assessment becomes an absolute nonsense, floor insulation is as important as roof insulation in regards heat loss, A photo record of the floor installation and any related work should suffice.Most of this EPC rating work seems to be quite the sham

I agree on all points. But if you look at an EPC, any floor insulation will have blanks where other energy saving measures will have a star-rating. It is not really accceptable for an assessor to use other than their own images, taken on the day of assessment. rdSAP assessments are very strictly audited and the algorithms in the software that calculates the rating are very accurate and sophisticated. But in my experience, the need to have solid evidence for everything means that in many cases, the assessor will err on the side of caution, and under-rate a property.

 

[Peterjay]

Prattling off the top of my head, the underfloor is the key imo due to the low flow temp required to feel comfortable, insulation as for any system is high on the list, balanced heat throughout creates pressure outwards, that contributes to less air movement and again a feeling of comfort, a pretty airtight home, not ridiculously so. The foregoing leaves an unhealthy house of stale air so in combination a simple heat exchanger to import fresh air will do the job and also not unduly affect the pressurising. All of this would make any form of heating more efficient. IMO, the ASHP should be the last on that shopping list unless you can afford to do it all. Insulation and a wooly jumper costs nothing further after purchase, yes ok you have to wash the wooly jumper.
A question, what make of heat pump ? What type of construction will the simple design take in regards materials.

The basic way to getting best performance from an ASHP to underfloor heating is to have an extremely well insulated, completely airtight house. That does mean that your house then needs an active ventilation sytem that conserves the heat from the stale, extracted air.

The house we are building is of SIPS construction, which means that it is effectively made from insulative material. This is lined with an airtight layer of additional, solid insulation on the walls and ceiling. The windows and doors are very carefully fitted to have no air leakage around them or from the seals. Even without heating, at this early stage, and even on a dull day, the house feels warm when compared with outside. Our design is monopitch, and is a simple oblong on one level and with no characterful dormers or fancy rooflines.

The heat pump is a Mitsubishi Ecodan, and our existing one has been running for over ten years with minimal maintenance.

 

[Peterjay]

This was what it looked like when he did his assessment and you can see the insulation at the edges!
As I said he was a w****r.
View attachment 41537

His name was Walter?
If he saw the floor at that stage there is obviously no excuse for recording the insulation.

 

[Peterjay]

Same here, learning lots from this. Still no wiser though on the best way to go.

I'm looking to the future, and would like some unbiased advice from someone, rather than a salesman, who all seem a bit snake oily on this.
I live in a converted fairly open plan barn, EPC is D, with an LPG boiler and wet underfloor heating, plus a log burner, all were installed on conversion in 2006, got a few pitched roofs facing wsw, and obviously the other side ese, and one small facing due south, which may not be useable due to planning, so looking to explore all the options. Solar, battery etc, two cars, open to EV as both commute about 30 miles round trip 3 times a week, plus mainly local with the odd road trip. No mortgage, nothing on finance etc. Both getting nearer to retirement age, though we won't

One issue may be that the spacing and actual lengths of pipework in a floor of that age, which was designed for an LPG boiler heat source It may be insufficient for the requirements of an ASHP.
The EPC is not really helpful on this; what you need is for a qualified person to assess the heat loss for the whole building. This is done my making precise calculations, based on the construction of your house roofs, walls and floors. They also need to take into account the ability of your pipework to deliver heat. That enables the size of heat pump, and hence the cost of installation to be calculated. Further to that, they can work out what flow temperature you would need, and overall, if theproject would be economically worthwhile.

To avoid the oily snakes, make sure you find someone who is prepared to show you calculations and based on those, to explain how you will benefit from the proposed installation.

 

[Jules59]

Insulation is by far the most important thing.
Its 11C outside today and the CH came on from 0630 to 0730 heating to 18C . Its now 1530 and the living room is still 17C - having not had the haeting on all day. The 50mm external insulation has made such a difference.
Just wish the stone floors were'nt so cold, but thats why we have socks isnt it.

I didnt realise Hive could run an old S-plan system until 2 yrs ago. So installed one . The increased flexibilty in CH usage has been very useful.
We are going out this evening so I wont put the heating on (if needed) until an hour before we return - whenever that will be.

We have a hot water cylinder heated by the oil CH boiler (its actually an Alpha cooker - a bit like an Aga but more efficient in that is not on permanently) and/or electric immersion heater. Our en-suite is the furthest room from the hot water tank and neither of us can be bothered to wait for the hot water to reach the tap and so, as there are only two of us in the house now, we simply dont bother heating the hot water cylinder for ourselves. We have an electric shower and an electric under-sink water heater in the kitchen/laundry. We just got use to having a quick morning wash in cold water.

I have thought about the changing the hot water system but I dont think it will be cost effective.

We do heat the hot water cylinder if we have guests staying - we're not that mean.

Having the solar panels installed in 2 weeks time - yay !

 

[Newbeeneil]

One issue may be that the spacing and actual lengths of pipework in a floor of that age, which was designed for an LPG boiler heat source It may be insufficient for the requirements of an ASHP.
The EPC is not really helpful on this; what you need is for a qualified person to assess the heat loss for the whole building. This is done my making precise calculations, based on the construction of your house roofs, walls and floors. They also need to take into account the ability of your pipework to deliver heat. That enables the size of heat pump, and hence the cost of installation to be calculated. Further to that, they can work out what flow temperature you would need, and overall, if theproject would be economically worthwhile.

To avoid the oily snakes, make sure you find someone who is prepared to show you calculations and based on those, to explain how you will benefit from the proposed installation.

When we were installing these systems we had to do the calculations to assess the whole house and make recommendations to the homeowner on what was the best way to claim the maximum RHI. The better overall performance the higher the payment.
Any decent installer should be able to produce their calculations before installation and they used to become part of the RHI documentation.

 

[Penninetrader]

sounds painful

He is if any of us get it wrong

 

[jimmiestan]

The basic way to getting best performance from an ASHP to underfloor heating is to have an extremely well insulated, completely airtight house. That does mean that your house then needs an active ventilation sytem that conserves the heat from the stale, extracted air.

The house we are building is of SIPS construction, which means that it is effectively made from insulative material. This is lined with an airtight layer of additional, solid insulation on the walls and ceiling. The windows and doors are very carefully fitted to have no air leakage around them or from the seals. Even without heating, at this early stage, and even on a dull day, the house feels warm when compared with outside. Our design is monopitch, and is a simple oblong on one level and with no characterful dormers or fancy rooflines.

The heat pump is a Mitsubishi Ecodan, and our existing one has been running for over ten years with minimal maintenance.

I'm told to service my ecodan [two ashp fans outside, ufh, well insulated house with hrc ssystem] EVERY YEAR -- is this truly necessary, do you think? jaylo

 

[Newbeeneil]

I'm told to service my ecodan [two ashp fans outside, ufh, well insulated house with hrc ssystem] EVERY YEAR -- is this truly necessary, do you think? jaylo

I’m sure by doing so you will avoid any nasty shocks should it fail but as I’ve already said I’ve not had my Dimplex serviced in the last 10 years but I do have a working knowledge of how it works and have rectified faults that have logged on the controls over that time. The most difficult was when the in-line heater tripped out and kept tripping the heat pump during really cold snaps but all it needed was to take the casing off and reset the trip switch.

 

[jimmiestan]

 

[Peterjay]

I'm told to service my ecodan [two ashp fans outside, ufh, well insulated house with hrc ssystem] EVERY YEAR -- is this truly necessary, do you think? jaylo

With the old feed-in tariff it was a condition that you had proof that the equipment had been maintained professionally each year. £200 should cover that, and over the first year or two, faulty parts that may be found should be replaced free of charge.

There are fewer things to go seriously wrong in an ASHP than an oil or gas boiler, and although loose electrical terminals can cause fires, lack of maintenance won't produce toxic gases, nor, in most circumstances will it reduce the efficiency of the pump.

The few things that need maintenance, such as the filter and the pressure vessels for the heating and hot water are common to all modern heating sytems, and many homeowners will know how to check or even how to replace these.

Having paid our installer for four years to simply clean out a Magnatec, top up the water circuit and clean down the grille on the external unit, I decided that I could do that. We are now in year 11, and the only thing replaced is the externally mounted control valve for the incoming water pressure; this isn't a part of the heat pump,although it was supplied with it. The user information that came with the installation implies that this will need replacing after a few years in any case.

Simple answer...yes, you should maintain it, but not necessarily by using a specialist.

 

[jimmiestan]

That echoes my thinking. Thanks.