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Author Topic: replacing economy 7 heating with ashp, any advice please?  (Read 5952 times)
RIT
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« Reply #15 on: December 13, 2015, 12:59:56 PM »

In terms of an Air to Air heatpump installation you would end up with an outside compressor and 1-3 internal header units, which connect to the compressor via 2 flexible pipes. The final configuration will depend on the layout of the house, but you are likely to want a unit in your main bedroom and your living room. As you can expect at least 3 times the heat out for the energy you put in it is likely that you would run the living room unit all day as a direct replacement for the rooms E7 heater and any stove you may now currently use.

The level of insulation you have seems to be key as you seem to be pouring heat into your house with the wide range of heat sources you have listed, most of which need lots of ventilation to operate or to deal with the damp they can cause.

For now try the following

   1) find a company that can give you a quote for an Air to Air solution so that you know its cost (and if its possible).
   2) find someone who can report on your insulation and quote you on the possible upgrades.

The problem for us on the forum is that we do not know your house in enough detail to say what should or could be done, all we can do is provide you with an every growing list of questions about your house and the possible choices you have. The starting list of questions/options will go something like this

   a) What do you have in your loft?        - Consider lots of loft insulation.
   b) Do you have unfilled cavity walls?     - Consider filling the cavity.
   c) What do you have on your floors?     - Consider carpets over wood.
   d) Do you have though walls air bricks?  - Consider blocking them as you make changes. If you are using lpg/Paraffin stoves DO NOT BLOCK THEM at this time.

and the list will just keep growing
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MisterB
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« Reply #16 on: December 13, 2015, 02:39:11 PM »

the lpg stoves are basically log burning stoves but fuelled by lpg (and designed to be fuelled by lpg!)

I use off peak electricity to heat the water. the pv keeps costs down during the day, even though its a higher day rate - we pay for less electricity than we used to because of the pv, I reckon around 60% of electric we use during daylight hours is 'free' over the year.


we have cavity wall insulation and around 150mm insulation in the loft. all rooms have carpets - property is detached, two floors (plus loft room), standard construction, around 7m x 10m footprint.
 
I will look at increasing loft insulation where I can access it. we have fully vented soffits front and back - I put them in about 10 + years ago when I replaced fascias and gutters, I am now thinking that doesn't help and might be better to reduce the vents 'significantly' - there weren't any vents originally, I added them thinking it was a good idea.

as for the ashp, I wouldn't want the 'head units' in the lounge/bedroom etc as theyre not the best things to look at so no chance of persuading the boss that its 'exactly' what we need !

« Last Edit: December 13, 2015, 02:57:00 PM by MisterB » Logged
RIT
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« Reply #17 on: December 13, 2015, 03:50:07 PM »

the lpg stoves are basically log burning stoves but fuelled by lpg (and designed to be fuelled by lpg!)

I use off peak electricity to heat the water. the pv keeps costs down during the day, even though its a higher day rate - we pay for less electricity than we used to because of the pv, I reckon around 60% of electric we use during daylight hours is 'free' over the year.


we have cavity wall insulation and around 150mm insulation in the loft. all rooms have carpets - property is detached, two floors (plus loft room), standard construction, around 7m x 10m footprint.
 
I will look at increasing loft insulation where I can access it. we have fully vented soffits front and back - I put them in about 10 + years ago when I replaced fascias and gutters, I am now thinking that doesn't help and might be better to reduce the vents 'significantly' - there weren't any vents originally, I added them thinking it was a good idea.

as for the ashp, I wouldn't want the 'head units' in the lounge/bedroom etc as theyre not the best things to look at so no chance of persuading the boss that its 'exactly' what we need !


I would say that the iBoost device should give you a good win in terms of heating the water from PV power (for a good 7-8 months of the year) and would have a quick payback, and throwing as much insulation into the loft as you can fit will help. The current recommendation is 270mm so just pile it high were you can.

If a full air to air system does not fit the general layout of the house for personal reasons an air to water system that feeds 2 or 3 water based radiators may fit better. This way you can replace key E7 storage heaters without having the whole house pulled apart at great cost, it will depend on your room layout.

Also if the issue is just how the heads look, have the 'boss' take a look at  

          http://www.cooleasy.co.uk/categories/wall-mounted/lg-aircool-stylist/

This is a unit that at least looks better than the standard 'blocks' and is designed to be installed lower down the wall. Even one such unit placed in a secondary room could be used to lift the core temp of the house by leaving the room's door open. It is not the most effective answer, but as you can expect to be using 1kwh of power for every 3kwh of heat you generate it is an option. Again it depend on how you like/wish to live, if you like having warm common areas in your house (hallway, landing etc) you can make savings by changing the way you heat these areas.

« Last Edit: December 13, 2015, 04:16:41 PM by RIT » Logged

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gnarly
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« Reply #18 on: December 13, 2015, 04:05:47 PM »

MisterB, can you estimate the amount of heat being used per year in KWh ?
This would be the sum of your electricity use plus an estimate at the amount of lpg / paraffin used.

I have installed an air-to-air unit in my living room, it has made the room much warmer and also a consistent temperature, and it seems very economical so far.  The whooshing air from the indoor fan takes a bit of getting used to (try to find a quiet model), but you can lower the fan speed. The compressor in the outdoor unit changes frequency according to demand and although barely audible, there are some times when it seems to resonate ever so slightly (it is mounted on a bracket on the external house wall).  Overall I am very pleased.

I'm using it with economy 7 and running it all night, the small increase in day rate is easily countered by massive savings at night.
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bxman
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« Reply #19 on: December 13, 2015, 05:15:47 PM »

"   massive savings at night. "

As far as I know none of the manufacturers of ASHP's  tell you that  the CoP varies dramatically with the outside temperature.

So running at night is not always be the bargain it would appear to be .

I think you will find  they are a little careful as to what figures they use for their calculations ,

I am sure there is a standard for  the industry and  indeed some manufacturers  may even  give the CoP at various ambients.
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MisterB
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« Reply #20 on: December 13, 2015, 06:59:17 PM »

ive been looking at the layout today and think a system with two ashp's (water) might give me a good option, our house is basically two almost identical sides separated by hall. stairs and landing. so my thoughts were to have two separate systems, each feeding one half of the house - it will keep water pipe runs and pipe sizes to a minimum.
would it also be quieter. or is fan speed noise the same - I was assuming one large hp would require a larger fan for moving more air than a smaller unit?

I am more than capable of installing (though admittedly not designing, on the basis I know nothing about heat pumps) two independent wet pipe systems, so internal install costs (rads etc) could be kept to a minimum

as a guestimate I reckon I would need 18kw system to totally heat, (based on a rough BTU calculation - old school !!) however if only background heating then of course a lot less.

rads like these??? seem a bit pricey for a radiator with a fan??

http://www.ebay.co.uk/itm/7-25W-Thermovec-Ultra-thin-fan-coil-radiators-Cooling-and-heating-Heat-pump-/321802480222?hash=item4aecec2a5e:g:G-8AAOSwRLZULVvZ
 
« Last Edit: December 13, 2015, 07:48:02 PM by MisterB » Logged
Countrypaul
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« Reply #21 on: December 13, 2015, 07:47:11 PM »

18kW system - how big is your house?  For our renovated house we are looking at a peak load of 6kW and that is for 250m2 admittedly that is using UFH and does not cover a rapid warm up time. How have you worked out the heat load, you say rough Btu calculation, sounds excessive to me which could lead to HP cycling and a killing of the efficiency. You should be looking at larger than normal raditors running as cool as possible - the opposite to a normal boiler where you end to run small radiators hot.

Using 2 heat pumps rather than 1 larger one means twice as much to go wrong, but then again unlikley to leave you completely without heat assuming they don't go wrong at the same time.
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MisterB
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« Reply #22 on: December 13, 2015, 07:51:35 PM »

18kw was a rough calculation conversion from a 60 000 btu ch system and trying to get the most from a lower heat system to compensate for lower radiator operating temperatures
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RIT
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« Reply #23 on: December 13, 2015, 10:41:25 PM »

18kw was a rough calculation conversion from a 60 000 btu ch system and trying to get the most from a lower heat system to compensate for lower radiator operating temperatures

The fact that you have found some low temperature forced air flow rads will mean that you should not have to build things larger to compensate. If your house is 7mx10m across 2 floors and a loft room 18kw seems very high, but only you know your house. In comparison my 7m x 5m 2 floor house after a good few years of insulation work needs a constant 2kw to keep warm at this time of year (South London), which will rise to 6kw if we get sub-zero temperatures. The one thing I do not have is a room in the loft which may have a big impact on your heating requirements. 

The first issue you will have is that I think the general regs allow the installation of a single external condenser, so having 2 may cause planning issues. One good thing is that I can at least point you in the direction of Navitron as they offer a range of units and you may find them helpful if you plan to do much of the work yourself.

   http://www.navitron.org.uk/fairland-orilux-12-8kw-air-source-heat-pump?gclid=CjwKEAiAy7SzBRD_lv7quOnr6XUSJAAOLkW6xjPmpDvZBsN39M2SWVAe5_8PkBHC4ZIL5PR2nQeErxoCNmrw_wcB

The T&Cs of this forum is that as it is provide free by Navitron we should respect their need to run a business and not post links to other vendors if Navitron can offer a possible service. So far I am not aware that this has caused any conflict between what advice members can give and what Navitron can offer as Navitron seem to be a very open company to talk to.
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MisterB
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« Reply #24 on: December 13, 2015, 10:58:42 PM »

thanks, the link I posted was only because I had just found them as opposed to not supporting navtron !!! I assume there are smaller ones available ie 2.5kw and prob a lot cheaper, and thanks for the info re only one condenser, I didnt know that !!

the loft room def compromises heat loss and the ability to insulate anything more than 100mm over a large portion of the loft and I do think the vented soffits don't help as they allow a large air flow at external temp and must therefore 'steal' a great amount of heat !! I will look at blocking them (they weren't originally there, I decided to install them!!)

I will def look to increase insulation levels wherever I can and cut down on drafts around the house, windows , doors etc.

my house is pretty much exposed to winds etc as it stands alone (nearest house is two fields away on one side and around a mile or so on the other three sides, so well exposed!) - the 18kw is def over the top but as I said I am working on the assumption that a larger ashp not working at max is better than small one over working ! I also wanted to 'future proof' the system in case of further development/extensions etc obviously I will look at getting a more accurate heat req when I have a specialist installer over to evaluate what our needs are
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DonL
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« Reply #25 on: December 13, 2015, 11:17:02 PM »

You do not have to use radiators with a fan. You can use standard panel radiators which are inexpensive. Obviously they have to be sized (larger) for the lower water temperature but they need not be that large if you use the double panel finned versions They then give a wonderful even heat to the room without the hot area around the radiator and induced draughts. With the radiator temperature being set according to the outside temperature they are on most of the time and you don't have the temperature cycling normally associated with on/off thermostatic control.
I used the Panasonic Aquarea heat pump (available from Navitron) and this has a variable speed drive to the compressor which may help it better match the required range of heat inputs. I have had no problems at all with it and am in the third winter.
IMHO you need to improve your insulation and airtightness as much as possible and then get proper calculations done to size the required heat input for each room against the RHI standard conditions and go from there. Once you have the heating requirements you can size radiators, distribution pipework and then you will have the heat pump duty and can size it properly. The work won't be wasted as you need the same heat loss calculations irrespective of the heating system. It's worth paying someone to get it done if you can find someone competent. Most heat pump suppliers should be able to provide the service, but I would want to see their input data as well as the results just to make sure.
Don
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Schuco solar hot water - 3300kWh/annum, 16 BP 4175N PV panels - 2.8kWp, log burner and back boiler and 18 Ying Li 235 PV panels - 4.2kWp, 42kW ground mount PV, 9kW Panasonic ASHP
RIT
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« Reply #26 on: December 13, 2015, 11:22:50 PM »

thanks, the link I posted was only because I had just found them as opposed to not supporting navtron !!! I assume there are smaller ones available ie 2.5kw and prob a lot cheaper, and thanks for the info re only one condenser, I didnt know that !!

the loft room def compromises heat loss and the ability to insulate anything more than 100mm over a large portion of the loft and I do think the vented soffits don't help as they allow a large air flow at external temp and must therefore 'steal' a great amount of heat !! I will look at blocking them (they weren't originally there, I decided to install them!!)

I will def look to increase insulation levels wherever I can and cut down on drafts around the house, windows , doors etc.

my house is pretty much exposed to winds etc as it stands alone (nearest house is two fields away on one side and around a mile or so on the other three sides, so well exposed!) - the 18kw is def over the top but as I said I am working on the assumption that a larger ashp not working at max is better than small one over working ! I also wanted to 'future proof' the system in case of further development/extensions etc obviously I will look at getting a more accurate heat req when I have a specialist installer over to evaluate what our needs are

My comment about links was in reference to the link I posted rather than yours, if someone is asking questions I can't see Navitron having any issues if third party links are provided to support the question(s). It is only really the members who are answering who should consider how they provide the answer.

If you are talking to someone who truly knows the market you should see if they know of a variable speed compressor, otherwise if you do supersize your installation all that will happen is that the external compressor will just stop and start a lot. Variable speed units are common in the air to air market (sometimes called inverters), but I do not know much about the air to water market.

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MisterB
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« Reply #27 on: December 14, 2015, 09:23:53 AM »

ive submitted a request to Navtron for a technical visit, so hopefully I should get a far more accurate idea of what is and isn't feasible/required. but thanks for all the replies, hey have been extremely useful.
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charlieb
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« Reply #28 on: December 14, 2015, 10:19:08 AM »

I'm using it with economy 7 and running it all night, the small increase in day rate is easily countered by massive savings at night.

Yes!   You're effectively moving from electric heating to electric heating if you go with any sort of heat pump, so as others have said, don't dump the E7 meter too quickly. If you do go with a 'to-water' heat pump and happen to have lots of space you could consider putting in a big thermal store/buffer tank so you can separate the running of your heat pump from the running of your central heating pump. Particularly if you have a big old house with decent thermal mass.     I don't know if this would pay back in your situation, but I know that's how I'd set up my heating if I was starting from scratch.  Not so much for the cost savings, but to do my bit for enabling more renewable electricity on the grid (Thermal Storage is MUCH cheaper than 'electricity' storage.)
 A few innovative supply companies are already bringing in special tariffs for people with decent sized thermal stores, and if you develop the 'must use every Wh' PV mania then it'll give you somewhere to dump your spare PV.        You could in theory go with something like sunamp's phase-change 'heat battery', but a 5,000 litre store is very likely to be cheaper and Sunamp seem to be concentrating on the immersun muewh market for now.   
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