Air Source Heat Pumps

albyota

Cardew, I'm not necessarly aiming my comments directly at you, but trying to give a balanced opinion from having experienced all types of heating, the costs, efficiencies, I am sure you are aware of my qualifications. and if I've read the posts incorrectly, I apologise, I'm trying to do that multi-tasking thing, like reading, typing and listening/watching the Telly (Grand Designs)

I am well aware of how most heating systems work, from domestic to large commercial buildings, controls, heat loss, cold bridging, U values, laws of thermodynamics, convection currents etc..
what I am saying is, UFH at low temperature and lots of water and acting as a large storage device works by mixing a small amount of 'new' heated water from a boiler or a heat pump with the return water flowing in the loops, via a blending valve, meaning the heat pump only has a small flow of water through the plate heat exchanger, the same principle as fan assisted convector radiators, or finned pipe radiator panels.
The point I was making about heat rising is, this is the only way normal radiators at any temperature work, as opposed to fan convectors directly blowing lower temp warm air, normal radiators need higher temps (your words) Fan convectors can produce the same room temps using lower temp, lower volume water, therefore increasing the efficiency of any heating system.

A heat pump can handle a constant flow of water through the Plate Heat Exchanger raising the return temp water by 12 degrees, i.e. flow 45 degrees, return 33 degrees, (or higher) so the UFH, fan convectors, larger radiators are constantly emmiting this heat into the room, there is no temperature fluctuation like gas or oil boiler cutting in and out.

albyota

zeupater wrote: »

Hi

Considering that a number of ASHP manufacturers claim that their units are easier to install than a gas boiler, why is it that installing a gas boiler costs less than £1000 (excl boiler cost) and installing ASHPs costs over £4000 ? ..... :think::whistle:

Z

Hi Zeupater,

I think you'll find that the manufacturers comments about being 'easier to install' than gas is, for developers, a new build estate would not need to install a large gas main into the estate, there is no need for a flue pipe, no expolsion, fire or carbon monoxide risk for housing associations etc.

ASHP's are still quite expensive to purchase (£2000-£4000) for the good quality heat pumps, the adittional costs will be for a heat pump coil type cylinder, which is a must with the low temp kit. The labour cost are actually the same, good quality hard working heating engineers are not cheap, not easy to replace and should be paid accordingly.

Cardew

albyota wrote: »

Cardew, I'm not necessarly aiming my comments directly at you, but trying to give a balanced opinion from having experienced all types of heating, the costs, efficiencies, I am sure you are aware of my qualifications. and if I've read the posts incorrectly, I apologise, I'm trying to do that multi-tasking thing, like reading, typing and listening/watching the Telly (Grand Designs)

I am well aware of how most heating systems work, from domestic to large commercial buildings, controls, heat loss, cold bridging, U values, laws of thermodynamics, convection currents etc..
what I am saying is, UFH at low temperature and lots of water and acting as a large storage device works by mixing a small amount of 'new' heated water from a boiler or a heat pump with the return water flowing in the loops, via a blending valve, meaning the heat pump only has a small flow of water through the plate heat exchanger, the same principle as fan assisted convector radiators, or finned pipe radiator panels.
The point I was making about heat rising is, this is the only way normal radiators at any temperature work, as opposed to fan convectors directly blowing lower temp warm air, normal radiators need higher temps (your words) Fan convectors can produce the same room temps using lower temp, lower volume water, therefore increasing the efficiency of any heating system.

A heat pump can handle a constant flow of water through the Plate Heat Exchanger raising the return temp water by 12 degrees, i.e. flow 45 degrees, return 33 degrees, (or higher) so the UFH, fan convectors, larger radiators are constantly emmiting this heat into the room, there is no temperature fluctuation like gas or oil boiler cutting in and out.

Hi albyota,

Yes I am aware of your qualifications and that you post sensible balanced posts.

However, due no doubt to your multi-tasking;), you 'didn't address the exam question'! and anyone reading your comment on UFH would be entitled to think that the warmth didn't go above 1.5 metres.

albyota

Cardew wrote: »

Hi albyota,

Yes I am aware of your qualifications and that you post sensible balanced posts.

However, due no doubt to your multi-tasking;), you 'didn't address the exam question'! and anyone reading your comment on UFH would be entitled to think that the warmth didn't go above 1.5 metres.

Sorry, yes, Under Floor Heating (UFH) (because that is what I have) only needs to heat the lower part of any room, where humans tend to be....most of the time, a ceiling does not need to be heated.

In a well designed new property, a ceiling void would be insulated therefore no heat would migrate through to the upper floor, aswell as zoning, ground and first floor should be on separate zones, but i am now descibing our future new build housing stock, perhaps another thread.

zeupater

albyota wrote: »

Hi Zeupater,

I think you'll find that the manufacturers comments about being 'easier to install' than gas is, for developers, a new build estate would not need to install a large gas main into the estate, there is no need for a flue pipe, no expolsion, fire or carbon monoxide risk for housing associations etc.

ASHP's are still quite expensive to purchase (£2000-£4000) for the good quality heat pumps, the adittional costs will be for a heat pump coil type cylinder, which is a must with the low temp kit. The labour cost are actually the same, good quality hard working heating engineers are not cheap, not easy to replace and should be paid accordingly.

Hi

I don't really follow this logic. Leaving aside the house heat delivery system, a 'boiler' type ASHP should simply require some change of the piping run in order to link into an existing system and the fitting of a flue pipe requires no more work than passing some pipes through a wall, so installation in it's most basic form should be no more complex than the work required to replace my floor standing gas boiler with a wall mounted one a couple of years ago. I agree that most installations would require a cylinder to be situated close to the HP boiler unit for hot water, however, this could just as easily be a standard £600 stainless steel unit as a 'posh' cylinder in a painted steel box with a logo, some flashing lights and a LCD temperature display on the front (a heating engineer's description, not mine ) costing a couple of thousand pounds, or more ... then again, for various reasons, some don't need to change their existing cylinder or location at all .

I do recognise that 'good quality hard working heating engineers are not cheap, not easy to replace and should be paid accordingly.' ... but surely this is just as true for gas heating engineers, so the cost/hour should be the same, possibly more cost for the gas installer if you consider the liability costs for 'expolsion, fire or carbon monoxide risk' and the need to be 'gas safe' registered ....

Anyway, I'm not sure, but isn't it also the case that the Ecodan unit you mention (being a non-split, self contained unit) can be installed by any plumber (or possibly a competent DIYer) and then commissioned by Mitsubishi for ~£400, this making the purchase & installation eligible for 5% VAT, which pays for the commissioning anyway (maybe also the RHI too when it becomes available) ?.

Z :think:

albyota

zeupater wrote: »

Hi I don't really follow this logic. Leaving aside the house heat delivery system, a 'boiler' type ASHP should simply require some change of the piping run in order to link into an existing system and the fitting of a flue pipe requires no more work than passing some pipes through a wall, so installation in it's most basic form should be no more complex than the work required to replace my floor standing gas boiler with a wall mounted one a couple of years ago. I agree that most installations would require a cylinder to be situated close to the HP boiler unit for hot water, however, this could just as easily be a standard £600 stainless steel unit as a 'posh' cylinder in a painted steel box with a logo, some flashing lights and a LCD temperature display on the front (a heating engineer's description, not mine ) costing a couple of thousand pounds, or more ... then again, for various reasons, some don't need to change their existing cylinder or location at all .

I was refering to you point 'easier to install than gas' and was describing new build properties where gas has to be brought in the the site (£thousands), what most manufacturers are gearing up to, is the new build market of some 200,000+ houses to be built in the next few years.

As it happens we do not fit ASHP's where gas is already available, 98% are village locations, retro-fit for LPG, Oil, or storage heaters, as well as complete new systems with UFH / Rads.
For retro-fitting in houses with LPG or Oil boilers there are additional costs for draining oil tanks and removing from site, the boiler is often in the centre of a house with the flue going up through the chimney, maybe asbestos present, connecting on to unknown pipe work / pipe size, in most cases a new hot water cylinder is a must due to efficiencies / lower running costs gained with lower temp water, and of course to comply with building regs, any new system must have the controls upgraded, i.e. TRV's on Radiators, 24/7 two channel programmer, new digital setback room thermostat, electrical test and part P compliance, MSC registration, completion packs etc.

A standard vented £600 cylinder only has a coil of 0.9m2 surface area, No good with heat pumps, the 'posh' type has a much larger coil, 3m2, plus thermo pockets for sensors, much more copper, to contain the same capacity of water means the cylinder would be either taller of fatter, 50mm foam insulated.

zeupater wrote: »

I do recognise that 'good quality hard working heating engineers are not cheap, not easy to replace and should be paid accordingly.' ... but surely this is just as true for gas heating engineers, so the cost/hour should be the same, possibly more cost for the gas installer if you consider the liability costs for 'expolsion, fire or carbon monoxide risk' and the need to be 'gas safe' registered ....

It is very true that a large percentage of GS/RGI's will be small, one or two man team type, sole traders, where the profit margin is a lot lower than a full MCS, BESCA, REFCOM, HVCA, CHAS, Trustmark, ISO 9001 type company with offices with admin staff, Techies, Sales, Repair, Service, ongoing training, H&S, van fleet etc.... so to make a comparison between a one man band and a SME company is not comparing apples with apples.

zeupater wrote: »

Anyway, I'm not sure, but isn't it also the case that the Ecodan unit you mention (being a non-split, self contained unit) can be installed by any plumber (or possibly a competent DIYer) and then commissioned by Mitsubishi for ~£400, this making the purchase & installation eligible for 5% VAT, which pays for the commissioning anyway (maybe also the RHI too when it becomes available) ?.

Z :think:

There won't be many people / companies just commissioning systems that have been fitted by someone else, how would they make any profit? how would they benefit? and when its your name that has to go on the form, who is ultimately responsible for the whole system, try getting a sparky to only sign of a DIYers new circuits or kitchen and bathroom work.

zeupater

albyota wrote: »

.... There won't be many people / companies just commissioning systems that have been fitted by someone else, how would they make any profit? how would they benefit? and when its your name that has to go on the form, who is ultimately responsible for the whole system, try getting a sparky to only sign of a DIYers new circuits or kitchen and bathroom work.

Hi

Thanks for reply .....

Regarding commissioning, my point was that Mitsubishi offer the commissioning service themselves (http://www.mitsubishi-aircon.co.uk/), and with the Ecodan being a selfcontained unit there should be no requirement for specialised connectivity testing as there are no external refrigerant connections only water connectivity to the heating system and that's probably why installers recommend them, it's less work than a split system (is this correct ?). I believe that the cost for Mitsubishi to commission and signoff is ~£400, so is there really any need for a specialised installer where a competent DIYer or a contract plumber & sparky could do the work ... where is the thousands of pounds of "added value" in most quotations coming from ?.

Thinking about the heating coil for a HP system, I'm pretty sure that a number (/the majority ?) of copper cylinder manufacturers offer coil upgrades to standard cylinders, so a twin coil solar cylinder costing ~£400 could have an UFH 3sqm coil upgrade for around ~£200 ... I think that's about right, a 200(ish) litre appropriate cylinder for ~£600 ?

Z

albyota

zeupater wrote: »

Hi

Thanks for reply .....

Regarding commissioning, my point was that Mitsubishi offer the commissioning service themselves (http://www.mitsubishi-aircon.co.uk/), and with the Ecodan being a selfcontained unit there should be no requirement for specialised connectivity testing as there are no external refrigerant connections only water connectivity to the heating system and that's probably why installers recommend them, it's less work than a split system (is this correct ?). I believe that the cost for Mitsubishi to commission and signoff is ~£400, so is there really any need for a specialised installer where a competent DIYer or a contract plumber & sparky could do the work ... where is the thousands of pounds of "added value" in most quotations coming from ?.

Thinking about the heating coil for a HP system, I'm pretty sure that a number (/the majority ?) of copper cylinder manufacturers offer coil upgrades to standard cylinders, so a twin coil solar cylinder costing ~£400 could have an UFH 3sqm coil upgrade for around ~£200 ... I think that's about right, a 200(ish) litre appropriate cylinder for ~£600 ?

Z

Hi Z,

the link you have provided is for Mitsubishi air conditioning, the air con side provide a commissioning service for the VRF systems, G150 controller and M2M series, this is a different depatment to Mitsubishi heating, http://domesticheating.mitsubishielectric.co.uk/home AFAIK, they do not directly provide a commissioning service for the Ecodan, that is what the AEI's are for, unless you know different.

Not sure what you mean by extra thousands? of pounds, if a unit costs between £2k & £4k of your zeupounds just for the outdoor unit to buy, (remembering these units are manufactured in the UK, Livingstone, Scotland) without a cylinder, (extra £600-£900, but its not gonna fit itself for that price) the system will also require a magnaclean filter, flow setting valve, isolating lever valves, flexible hoses, additional pipe & fittings, pipe insulation, 2 x grundfos pumps, 2 honeywell motorised valves, T&PRV, expansion valves, FTC controller, programmer, digital room stat, electrical isolator, Switched fused spurs, MCB, cables, 25% Sentinel antifreeze/inhibitor, removing old cylinder, header/storage water tanks, converting from vented to unvented / sealed system, labour, two man team for 2+ days, Van, fuel, and 22% -30% markup, MCS registration, completion pack, a complete turnkey solution. Plus the peace of mind of only dealing with one company. all for an average £6k to £8k.

If a company is quoting a lot more, in the current financial climate, beware!

p.s. if you stick a 3m2 coil in a 200L cylinder you will not have 200 litres anymore :eek:, for the smaller heat pump, you can get away with slightly lower efficiency by using a twin coil tank joining both coils together about 1.8m2.

AL

TiredGeek

albyota wrote: »

2 x grundfos pumps,

Little bit off topic question here: what size pumps would you specify for the Ecodan 14kw units?
I have four 15/60 Grundfos Alpha 2L feeding the two ASHP on 28mm pipe and can only achieve ~25 L/min flow rate.
Short pipe runs, low loss header, two pumps per ASHP, so no restrictions really.
Obviously that's on the low side of what Mitsi specify for the units, 20 - 40 L/min, so I was wondering if my pumps need upgrading to something more like 25/60 to get a better flow rate.....
15/60 is what the installer say is right btw.

zeupater

albyota wrote: »

Hi Z,

the link you have provided is for Mitsubishi air conditioning, the air con side provide a commissioning service for the VRF systems, G150 controller and M2M series, this is a different depatment to Mitsubishi heating, http://domesticheating.mitsubishielectric.co.uk/home AFAIK, they do not directly provide a commissioning service for the Ecodan, that is what the AEI's are for, unless you know different.

Not sure what you mean by extra thousands? of pounds, if a unit costs between £2k & £4k of your zeupounds just for the outdoor unit to buy, (remembering these units are manufactured in the UK, Livingstone, Scotland) without a cylinder, (extra £600-£900, but its not gonna fit itself for that price) the system will also require a magnaclean filter, flow setting valve, isolating lever valves, flexible hoses, additional pipe & fittings, pipe insulation, 2 x grundfos pumps, 2 honeywell motorised valves, T&PRV, expansion valves, FTC controller, programmer, digital room stat, electrical isolator, Switched fused spurs, MCB, cables, 25% Sentinel antifreeze/inhibitor, removing old cylinder, header/storage water tanks, converting from vented to unvented / sealed system, labour, two man team for 2+ days, Van, fuel, and 22% -30% markup, MCS registration, completion pack, a complete turnkey solution. Plus the peace of mind of only dealing with one company. all for an average £6k to £8k.

If a company is quoting a lot more, in the current financial climate, beware!

p.s. if you stick a 3m2 coil in a 200L cylinder you will not have 200 litres anymore :eek:, for the smaller heat pump, you can get away with slightly lower efficiency by using a twin coil tank joining both coils together about 1.8m2.

AL

Hi

Commissioning service ... my mistake, wrong link, but, from checking a wellknown distributor website it looks like AEI commissioning is available for <£400 anyway.

I dont think that I could find an installer who would accept zeupounds, they're only legal tender in the zeuhouse, we'd need to use a 'foreign' currency if we bought a unit and account for the purchase as an import which would show a negative balance of trade for that month ... if you accept zeupounds then i'll envoke a little quantitive easing and print a few then have an ASHP tomorrow if it suits .....

I follow the logic regarding the additional costs, however, what's to stop the system being fitted as a replacement for, or even, alongside an existing gas boiler ? ... also, why would you need to change the system to unvented, it could already be unvented, or couldn't it run on a standard vented setup ? ... again why £600-£900 for a cylinder, I'm not in the trade & could buy a twin coil copper solar 210l cylinder for <£350 and add a 3sqm coil for <£200 the last time I looked, so it should be £600max and this could already be in place if well planned with a solar thermal install ... I have a 28mm magnaclean unit on the circuit already and many others would have filters too, I'd guess that I wouldn't need two either .... the circuit is S-Plan, already has all control gear and was modified to have a bypass valve fitted when the HE boiler was fitted less than two years ago ... the install of the replacement gas boiler took two days of a gas fitter/plumber and probably a couple of hours of an electricians time (+apprentice) and included rerouting the boiler pipework and the fitter bricking up the floor mounted boiler's balanced flu hole and all this was done for thess than £2k inc VAT, so roughly £1k to cover labour/overheads and margin for the company.

Regarding the volume of the tank, what about a 210l tank with a 3sqm coil to compensate, or alternatively just having using a finned coil ? ... anyway, it makes very little difference to most, a 28mm diameter tube coil with a 3sqm surface area would be 34.1 metres long and displace 21l, so let's call a 210l tank 190l capacity, a reduction of only 10% (more on a smaller tank, less on a larger one) ....

Margin of 30% ? ... well that's probably okay when selling something with a price similar to that of a TV, but the installers who will survive when RHI matures will be those who soon discover that when selling items which cost the same as a small car, it's probably a little advantageous to reduce the margin which they were used to on cheaper heating boilers, increase sales, expand and make more profit rather than be uncompetitive, sell very little, and go to the wall :whistle:.

Z