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Air Source Heat Pumps

Discussion in 'off topic' started by mikechadwick, Jun 27, 2022.

  1. PsB

    PsB Citizen of Nowhere™

    Assuming the water circulated by the gas fired system is hotter and the water circulation pump is the same, then the higher water temperature provides the room with more kW (and consumes more in the way of fuel), no? Doing the same job with lower temperature water and the same flow would require a bigger heat exchanger (radiator) in the room to get the same number of kW into the room. So the two systems are not comparable.
    I still don't get it.
     
  2. hifinutt

    hifinutt hifinutt

    interesting , my wifes college just had a big fire a few days ago that caused a lot of damage cused by a fault with solar panels !!
     
  3. hifinutt

    hifinutt hifinutt

    i am curious about this , i have spent just under 10 years curing mould in a house with no draughts . now it has tricle vents , roof vents etc etc . if i block them all up the mould will come back !!!
     
  4. martin clark

    martin clark pinko bodger

    Of course it will, that was the point of my last post above - assuming that (if topical/limited to certain spots) you got to the root of any other causes of dampness.


    Background ventilation is essential; but it's much better when you have control of it.
     
    Snufkin, hifinutt and IanW like this.
  5. martin clark

    martin clark pinko bodger

    You have it right.

    Once you have a building in a fairly steady-state the heat input is ...very moderate, and low-level. (hence the benefit of heat reclamation! two thirds of teh total loss is in the ventilation requirement, as far back as uk build regs 2006 and before)

    Higher flow temps only allow faster changes in internal air temp; it represents more power input, basically - usually much more.*
    Then again, few people really bother to think how TRVs and thermostats work - 'I'm cold/ whack system wideopen/ 'now I'm hot'/ turns down or opens window... the thing the thermostat does for you, far, far more efficiently.

    The way to use the more efficient systems - is pick a set-point (or a profile of setpoints, even any gas boiler controller in the last 15yrs lets you do this!) - then leave the damn thing alone to settle... yes it might take hours. Then leave it on. Always. That's it, that's all. Tweak after a week or two to finesse it, that's all.

    The point about heatpumps, air or ground-source, is that then they are just providing the smaller make-up to maintain the profile. At that point the CoP is approaching 3, i.e. 1kw electrical input is providing as much as 3kW sensible heat output. This is why Heatpump systems also revert to using large tanks of dmoestic hot water storage - to creep-up efficiently on supplying peak demand, not just being expected to provide everything, right now. Averaging of demand.


    * I have a gas boiler
    I used my IR thermometer to check all my rads are balanced (10degC diff across each, at max flow) and that return flow is 50degC. They are only normal size rads. In a slice of 1770ish house, single-glazed leaky sashes and all. Yes, from cold on a cold day it can take 3-4hrs to come up to temp on a cold day (eg after a week away in winter). But because otherwise, it runs to a setpoint profile (21degc in the lounge, or where-ever I take the wireless thermostat, for as much as I expct to be at home +an hour either end) as a result the boiler is always right where it is condensing to best effect; and while same boiler provides all hot water on demand.. my gas bill is minute, while I am comfortable.
     
    dan m and PsB like this.
  6. martin clark

    martin clark pinko bodger

    (unitl recent unit prices) That's what, >70KwH electrical input - indicates something seriously wrong with the way it is set up or commissioned. As net input to a heatpump system, that order of magnitude should broil you. Whats the building like/ age etc?
     
  7. Somafunk

    Somafunk pfm Member

    I've posted regarding heat pumps on another old thread, I'll find it and copy/paste below - contains all my replies to multiple posts so may not make sense.


    "In 2013 DGHP Housing association removed my open fire with back boiler and 6 radiators which gave enough heat to have windows open in winter whilst sitting in pants and fitted a Daikin altherma heat pump system and new radiators to my uninsulated and draughty late 80’s built 1 bed bungalow in Galloway, part of some bullshit government scheme to claim they were going green, there is no gas supply where I live. My electricity costs went from £10ish to £40+ per week in winter as the system doesn’t work in low temps nor with the build quality in the house. Two years ago they fitted a Tesla power wall battery to attempt to offset the running costs, saved a couple of £ but still bloody useless.

    So I knocked back through the bricked up fireplace and fitted a wood burning stove/lined the chimney as I have access to unlimited seasoned logs from a friends farm/forest. This caused much upset from the housing association and they threatened me with eviction so I paid for an independent report regarding the fitting of such a heat pump to my poorly insulated house which showed that it was an unsuitable system to install and should not have been fitted.

    In a new house built to modern insulation standards with underfloor heating I imagine they are a great choice but not in a 40yr old draughty poorly constructed and insulated bungalow, especially as I have secondary progressive MS and need heat & warmth

    The housing partnership that took over dumfries & galloway council housing stock received a green initiative grant to remove coal/open fires from the houses that were not on mains gas, aka greenwashing. They claimed it would be cheaper to run and provide sustainable heating and hot water solutions. Utter ****ing bullshit dressed up as "look at how green and environmental our housing stock is"..............I'm convinced someone on the board of DGHP got backhanders to ensure the refit went ahead but im not allowed to repeat this otherwise ill be taken to court....a mate used to be in charge of housing repairs so im 100% convinced of what I was told.

    But the claim made by "experts" was that you can't get water temperatures >50C from heat pumps or retrofit them to existing buildings, laws of physics etc. This is incorrect. Technology is advancing rapidly in this area, and what was true 5 or 10 years ago is not necessarily true any more.
    No one was saying you can’t retrofit them to existing buildings at all, in fact they can perform very well on a £ vs kWh cost compared to gas or oil when retrofitted to buildings built before the revision of building insulation regulations 2010, on one provision that is stated time and time again in manufacturers guidelines and is a recognised industry standard, is insulate….insulate……insulate before consideration and ensure you are able to fit underfloor heating, the thermal efficiency of using heat pumps with existing type 22 steel radiators is very poor, aluminium radiators are slightly more efficient but to get the full benefit of such a system you should consider under floor heating laid on top of a well insulated floor.

    A close friend recently built his (croation company built/designed, he just paid for it) dream forever modern home kinda similar to a huafhous but cheaper - no less quality though and the house is massive (compared to mine anyway) at 350 square meters compared to my paltry 50 square meters. Super insulated with special triple glazing and polished concrete underfloor heating throughout and he’s using a heat pump system not much larger than what I have fitted yet his heating/electrical costs are a less than 50% of what I spend, despite myself also having a Tesla power wall battery fitted to offset my running costs as it stores cheaper off peak electricity to feed into my daily running costs.

    The Tesla battery has saved me a few ££ but the money spent on buying and fitting it would have been better spent by the housing association on replacing the thin air gap 40yr old double glazing and lifting the suspended wooden floors and insulating underneath, also fitting more insulation in the attic, perhaps even fitting solar panels to the roof as the pitch and location of the house is ideal to take advantage of the sun all day but that’s not sexy enough nor as headline grabbing as the housing association proclaiming that “we’re bringing our housing stock up to modern environmental standards by fitting TESLA batteries”. I imagine this was done through the use of environmental grants that ultimately every single householder are subsidising through their electrical bills - the opportunity for grand kickback scams given to “independent companies” are wide open and I’m sure they are being exploited to our detriment.

    Quite a rant but it really pisses me off how much an ill thought out improvement for environmental reasons has ended up costing me over 200% more in electricity costs per year and using far more electricity to rub salt into my wounds. Previously I used approx 1500kwh of electricity a year in my tiny 1bed bungalow when I had an open fire/back boiler, last year I used 4600kwh. "

    As an aside I see PsB in the other thread regarding heat pumps asked pretty much the exact same questions as he asked in this thread (see below), Just trolling?, or genuinely interested but not listening to replies?.

    https://pinkfishmedia.net/forum/threads/domestic-heat-pumps.256192/
     
    Snufkin likes this.
  8. martin clark

    martin clark pinko bodger

    @Somafunk - thanks for that; I'll have a think & consider.
     
  9. PsB

    PsB Citizen of Nowhere™

    I really don't want to get into an argument with you about this: I'm not trolling, and I'm (still) very interested in understanding why there is this perception that HPs only work in well insulated buildings. I remember your explanations from the last time the subject came up here and have read them again now, but they miss my question. ISTM building insulation and efficiency of the heating system are two different issues, although they both affect your heating bill. In other words, building isolation determines how many kW of heat you need to maintain 20C in your home: could be 5 kW for a well insulated house, or 15 kW for a poorly insulated place of the same size. The efficiency of the heating system will determine how many kW of primary power (whether electricity or gas, it doesn't matter) you need to expend to get that. A well set up heat pump normally has a COP around 3 or better, so you should get 15kW of heat with 5 kW of electricity, regardless of how draughty the house is.
     
  10. Sean K

    Sean K pfm Member

    They're absolutely standard here in NZ and have been for many years, even in the old (late 19th/early 20th century) poorly insulated housing stock that's common; think wooden tent. The climate down here at he bottom of South Island, where the winters are at least as cold as in the North of England (I'm from Manchester and lived in Hull and Sheffield before moving out here in 2005), and they work perfectly well. The idea they won't perform well in a UK climate is simply wrong.

    They're pretty flexible and can be ducted to several rooms, either by simple fan or by a separate heat exchanger unit for each rooms; obviously the logistics will vary depending on your house construction. Daikin and Mitsubishi are popular brands. I've had three fitted in various houses and they've all run like clockwork, the only maintenance being 1) hoovering the dust filters every month or so, which is a five minute doddle of a job (some are even self-cleaning; when clogged, the filters are motor driven across a cleaning comb) and 2) washing the exchanger fins every year or so to maintain peak efficiency, although most people don't bother that often and here, there are firms who come and do that for you for a very reasonable fee, along the lines of someone cleaning your gutters, sweeping the chimney, etc.

    Agree re the point about them being less efficient in poorly insulated homes applying to to any heating method.
     
  11. molee

    molee pfm Member

    Interesting point about cleaning. Have you had to clean out the ducting or had occasion to inspect it?
     
  12. Ellenor

    Ellenor pfm Member

    It’s funny isn’t it how people take insulation seriously when they’re thinking of having a heat pump installed.
    Has it occurred to anyone that you can still take these measures with gas central heating? A quality modern condensing boiler running weather comp with oversized rads in a properly insulated building is what I recommend for the time being, if on natural gas of course.
     
    Richard Lines likes this.
  13. Sean K

    Sean K pfm Member

    I don't have a ducted system, just one internal exchanger unit.

    I can't imagine anyone having to inspect the ducting, as I say, the filters are rather good.

    it sounds like they're still uncommonin the UK (along with having a government not composed of utter %!$@s). Here, prope just fit them and forget about them; they generally go on forever. After all, it's basically really old technogy. They were ubiquitous when I got here in 2005.
     
  14. mikemusic

    mikemusic pfm Member

    That could be my next task
    :)
    This house loses too much heat. Fix that and see how we go with mould.
    Air exchange unit seems a good if pricey item
     
  15. dweezil

    dweezil pfm Member

    Could be worth running a dehumidifier?

    I had a tenant who insisted on having a window open and didn't want to pay for heating, easiest way out was a dehumidifier in winter.

    I've blocked all the vents here and close unwanted chimneys but don't get mould with a base settings of 5C.
     
    mikemusic and hifinutt like this.
  16. hifinutt

    hifinutt hifinutt

    yes we nearly resorted to a dehumidifier but seems to be under control with ventilation thanks
     
  17. Ponty

    Ponty pfm Member

    Quite. My new place runs underfloor heating from a gas combi boiler. It’s so efficient, in part because the house is so well insulated and just doesn’t lose any heat which is put into it.
     
    Ellenor likes this.
  18. molee

    molee pfm Member

    Ah, I saw a reference to ducting in your post and thought you had some. The issue is not so much dirt, as you say the filters sort that out. Rather condensation can build up especially in concertina type ducting or where there are inadequate or adverse gradients leading to heavy mould growth. Mould can cause more harm than cold.

    I think they are finding that the balance between insulation and adequate ventilation is a particularly vexing one. A 21 century equivalent of when fireplaces were introduced to thatched dwellings. Where previously, smoke would drift up from the floor through the thatch and fumigate/dry the reed- smoke going up the chimney allowed mould to grow in the thatch and spores would drift down on to the unsuspecting dwe.lers.
     
  19. mikemusic

    mikemusic pfm Member

    May not need one of course
    Many years ago I changed single to double glazing a few windows at a time.
    The more double glazing I had the less moisture.
    Some draught proofing too
     
  20. dweezil

    dweezil pfm Member

    Same here, the first winter was a bit rough but once we'd finished basic decorating i had a go with all sorts of draught proofing strips, probably spent a tenner for a massive improvement.

    To see if the vents were doing any good i taped plastic bags over them at first.

    If doing that today smoke / CO monitors are vital.

    Current target is to make the oil last 50% longer next winter.
     

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