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

richardc1983

Before u spend expensive money on dehumidifiers look at the drimaster

lovesgshp

belleooo wrote: »

Hi, property is 155 m2? We have been quoted for a Mitsubishi pump that's 14kw. We currently have an LPG system which we only use for the hot water, too expensive to run the radiators. All but 3 of the radiators are sufficient. The 3 that aren't are being replace with larger ones. And yes, we need dehumidifiers pretty badly. Looking after dad full time, so we now need a warm house for him. I want to move away from LPG. The other alternative is biomass.
Thank you for your replies.

14Kw is quite high for a house of that size, but saying that, with the low insulation, then it may be a good choice.
Look into the fan coil option for the rads you need to replace.
You will find with the heat pump that the heat level is more stable in the house, so before you go with the dehumidifiers, see how everything works out.

[Deleted User]

belleooo wrote: »

Hi, we've had a quote for a air source heat pump. The guys who gave us the quote have closed offices down for Christmas now, so will have to wait a few weeks before I can talk to them. Our concerns were insulation. 100 year plus granite property in rural Scotland. Cannot have cavity wall insulation. Had loft insulation but has bedrooms are in the loft, there isn't much roof covered. Also has double glazing. There no floor insulation. Property is very cold in the winter, has condensation problem upstairs. Bearing in mind the lack of insulation in the walls, would an air source heat pump be sufficient? or does it pump heat out that slowly it would be lost through the walls before we got any benefit from it? Our other alternative is a biomass boiler, but even with RHI it is very expensive. Thanks.

Also Scotland here... Rural, detached, 100+ years old with large rooms and v high ceilings etc. Used to be on LPG @ ££££s now Mits Ecodan coupled to 13 Dimplex SmartRad fan coils, UFH in bathroom & towel rail. 4kWp Solar PV on the roof so total annual electricity useage less that £1000, low 8000s kwh. Flow temp during recent cold snap reached high 30s with heating running 7hrs weekdays, 12hrs weekends to maintain house temp >17c to 21c max depending on time of day etc...


PS a mate recently installed Biomass, running costs not hugely cheaper than oil but massive install cost + complexity despite RHI.


Cardew is correct, if not installed correctly you'll wish you stuck with what you had...


Cheers

John_Pierpoint

How many air changes per hour are you getting - the mention of mould suggests one of two situations

The house is drum tight
or
more likely the draft proofing is pretty poor the internal doors are open, or not good fits and the befrooms are unheated especially in the north East quadrant of the property (where all the warm "sweatiness" of the occupation migrates).

Robwiz

richardc1983 wrote: »

Before u spend expensive money on dehumidifiers look at the drimaster

Noo! Don't bother with a Drimaster. They might be ok in rental properties but for owner occupiers they are bad news. A Drimaster will introduce air at loft temperature into the house and will require extra heat input to compensate. A combination of extraction in wet rooms and a dehumidifier is more effective in our experience.

John_Pierpoint

The problem in rental properties is tenants trying to "save" money by drying clothes on radiators and airing racks. They are failing to understand anything about the latent heat required to evaporate the moisture that then transfers to the black mold cold bridges and the window glass - the fastest way to escape into the great out doors.

I've seen identical flats, one with no problems and the other a complete mess, with the wallpaper coming off the walls.

Robwiz

John_Pierpoint wrote: »

The problem in rental properties is tenants trying to "save" money by drying clothes on radiators and airing racks. They are failing to understand anything about the latent heat required to evaporate the moisture that then transfers to the black mold cold bridges and the window glass - the fastest way to escape into the great out doors.

I've seen identical flats, one with no problems and the other a complete mess, with the wallpaper coming off the walls.

I agree. Same with people believing that by having the temperature on a higher setting it will prevent condensation. All that happens is that the warmer air can hold more water vapour which condenses out when the temperature falls or on colder walls or windows.

richardc1983

Robwiz wrote: »

Noo! Don't bother with a Drimaster. They might be ok in rental properties but for owner occupiers they are bad news. A Drimaster will introduce air at loft temperature into the house and will require extra heat input to compensate. A combination of extraction in wet rooms and a dehumidifier is more effective in our experience.

I disagree completely with you. I've had one running for several years now and it's cured the issues we were having. We have the drimaster heat and we would rather have fresh filtered cooler loft air than run an expensive dehumidifier which we've tried in the past that made no difference. we've noticed no difference in our gas bills from the heating yes the landing is a bit cooler but we have no condensation at all on our walls or windows and the air in the house is much healthier. A dehumidifier just recirculates air in the same room. positive pressure fans pressurise the house and push stale damp air out of any gaps or air bricks which for us has meant a warmer house overall. It's the best £200 we've ever spent and like I say running costs of a dehumidifier which are expensive to run didn't work for us. Don't knock a product unless you have tried it yourself. The reviews all over speak for themselves. Curing damp of its due to occupants is by ventilating and air changes... A dehumidifier will struggle to do anything without air changes which in today's world of sealed houses and double glazing is why there are so many issues. Before we would have extractor fan in the bathroom that made no difference at all and we would leave windows open all the time which made the house cold but it wasn't enough. I can honestly say positive pressure ventilation has been the best thing we ever did. The loft air is always 3c Warmer than outside the house and the little heater tempers the air if it drops below 10c but this is on a timer to only run on a morning and In the evening and this isn't rwquired it's just for our comfort.

http://www.doyourdream.co.uk/2013/01/installing-a-drimaster-heat-piv-system/

inasnum

Robwiz wrote: »

Noo! Don't bother with a Drimaster. They might be ok in rental properties but for owner occupiers they are bad news. A Drimaster will introduce air at loft temperature into the house and will require extra heat input to compensate. A combination of extraction in wet rooms and a dehumidifier is more effective in our experience.

Not the case in my house - works a treat!
It does introduce cooler air and yes you'll have to heat that but I've found unless its freezing outside you don't notice a drastic difference.
I tried dehumidifiers and unless we were drying clothes it didn't get much moisture out the air. The drimaster is far superior!
We also have an bathroom extractor.
Besides all that fresh air is good, and its definitely better in winter drawing it from the loft (which is slightly warmer) than opening up windows!

TiredGeek

belleooo wrote: »

Hi, we've had a quote for a air source heat pump. The guys who gave us the quote have closed offices down for Christmas now, so will have to wait a few weeks before I can talk to them. Our concerns were insulation. 100 year plus granite property in rural Scotland. Cannot have cavity wall insulation. Had loft insulation but has bedrooms are in the loft, there isn't much roof covered. Also has double glazing. There no floor insulation. Property is very cold in the winter, has condensation problem upstairs. Bearing in mind the lack of insulation in the walls, would an air source heat pump be sufficient? or does it pump heat out that slowly it would be lost through the walls before we got any benefit from it? Our other alternative is a biomass boiler, but even with RHI it is very expensive. Thanks.

Sounds very much like our houses are similar

ASHP is possible for your house, but what is your main reason for looking at it?
If it's running costs, then it may well be cheaper but installation costs far exceed oil.
We worked on the principal of it being 33% cheaper to run than oil and not the 75% we were being told by salesmen. Don't know if it's correct because we never had any other heating fitted. We're certainly cheaper than our friends with smaller houses though
Our main reason for going with it was oil thefts in our area and the fluctuating oil prices.

Radiators is another issue.
Who told you the radiators you have are correctly sized? (apart from those you mentioned)
I would say ALL your rads are undersized. What works for oil and LPG with flow temps of about 75' does not work for about 40' flow. For instance, my house isn't all that much bigger (~170m2) and we have 2 x 14kw and 39 rads (most doubles!).
You must factor in new radiators, possibly fan convectors to save space and installation costs.

The thing you need most is full loft insulation. I'm guessing you have T&G panelling in the bedrooms. Two options: 1- remove, insulate and refit. 2 - insulate over the T&G and lose some headroom (there are some very good very thin insulation products out there now, but costly).

As for your condensation issues, have you had the roof checked over?
With solid walls you could have a leak from a gutter (rowan) or roof that's letting water percolate into the wall and that will show in the house as damp. This would also make the wall colder which would lead to condensation inside the rooms.....

In summary: it's possible to use ASHP to heat an old Scottish rural property, but it might not be the best solution in all cases.

PS: whereabouts are you? I'm on the north coast.