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Builders
We're considering installing an air source heat pump. The installer is putting together a quote and will be getting back to us.
We found him via 'Which' trusted traders - a scheme I trust vastly more than Check a trade and the like.
Which do proper vetting and inspect a random job carried out by the builder. You can't put in a fake review.
We're also removing our fireplace as part of the process - you can lose a lot of heat up a chimney - and for a heat pump to be cost effective you have to have really good insulation (which we do have) and minimal heat loss though chimneys, etc.
The fireplace was long overdue for removal. Hasn't had a fire for at least 38 years....
We've been using the Federation of Master Builders website and also the Government Trustmark site. Both of involve actual vetting.
We found him via 'Which' trusted traders - a scheme I trust vastly more than Check a trade and the like.
Which do proper vetting and inspect a random job carried out by the builder. You can't put in a fake review.
We're also removing our fireplace as part of the process - you can lose a lot of heat up a chimney - and for a heat pump to be cost effective you have to have really good insulation (which we do have) and minimal heat loss though chimneys, etc.
The fireplace was long overdue for removal. Hasn't had a fire for at least 38 years....
We've been using the Federation of Master Builders website and also the Government Trustmark site. Both of involve actual vetting.
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When we have a quote, we're going to walk down the road and listen to the one the installer has - he says his is quiet, but there are now even quieter ones.
It's probably not worth replacing your boiler if it is working well. Our boiler is old and on its last legs. There's always a carbon cost to replacing things, and that has to be taken into consideration.
And you really must have good insulation.
What I'd do regardless is to check your loft insulation. Then tell me how thick it is....
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You can buy rolls to fit between rafters now. (was much harder when we did ours)
You'd be surprised the difference the extra makes. A lot of cold corners in our lounge vanished. Which I hadn't expected as we're a two storey house.
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Are your "boilers" actual steam producing machines or has that come to mean what we call a "heating system"?
In Ukiah we have an "airtight" wood burning stove that takes the place of a regular fireplace. Ours is cast iron with a double vented stovepipe. No air from the interior of the building goes through the stove. It has a double vented pipe vents hot air out in a ring around the the incoming cold air thus heating it before it gets to the combustion area. I know that a lot of people retrofitted airtight "inserts" into old fireplaces which makes an incredible difference. The airtights burn wood much more efficiently as well, our chimney sweep says there is almost no carbon buildup on the pipes, so they only really need cleaning every few years.
In SF we have gas burning airtight stoves, which are very efficient when we need them, which is seldom. It is usually so mild here that we have the windows open year round.
Up in Ukiah a squirrel got into the attic at one point made a big mess of the insulation resulting in a patch of it getting removed. During the hot summer you could feel the ceiling and feel exactly where that patch was!
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A gas boiler heats water that then flows through radiators and also provides hot tap water.
They're pretty much the default UK heating system. They work well, but they have to go. We can't afford to keep burning fossil fuels. (the timing of what we need to do is incredibly tight and the odds of us making aren't that good - and part of the problem is that most people aren't even aware that there is a problem, and if they are aware, then don't know what lifestyle changes they need to make. It's scary.)
YOur double vented pipe sounds very efficient.
I suspect wood burning is viable for you as you'll have dead wood on the ranch that needs clearing to reduce the fire risk.
In the UK in winter, wood burning stoves in cities are a massive source of air pollution. The other problem is that there are now so many of them that some of the wood is coming from unsustainable sources.
In the UK, I think people forget that insulation also keeps out the heat in summer - we're still getting used to the idea of summers that are too hot. The last few have been pretty bad - it's hard to get much done as the heat makes us tired.
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How cost effective are the heat pumps, do you know? I think they can be most useful for people who aren't on mains gas.
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In the UK, there's a government subsidy that pays you back the difference in cost between the heat pump and a boiler (albeit over a 7 year period)
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they're very rare here, it's usually done to radiator systems.
For me the main drawback was the fact that they move dust around and I'm asthmatic with a particular problem with dust.
However, I imagine they're massively cheaper to install. And you get the advantage of air-conditioning in the summer.
I've set up a face book group for discussing ways of reducing carbon footprints. I've just invited you. Would you be willing to write a post on your experience of air to air heat pumps? (there's a tagging system so that you can tag it to help people find posts on particular topics)
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They are indeed much cheaper to buy and install than the more complicated options. So much so that when somebody says heat pump here, it's a pretty safe assumption that that's what they mean.
But as you say, cooling in the summer. We get a few more really hot days and nights each year here in Chch than we did in Cambridge, and the cooling mode is fantastic.
Yes, very happy to write up my experience.
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My friends' system is air-to-air, but knowing what I do of them I imagine this is more down to sales techniques and installation costs than anything else.
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Background & Climate
I spent the first 33 years of my life in the UK, in Edinburgh and then Cambridge.
Since 2011 I have lived in Christchurch, New Zealand. We're 43 degrees south of the equator, the same sort of latitude as southern France or northern Spain.
Heat pumps are quite common here and are gradually replacing open fires and log burners. (Air quality is on the agenda, but slowly; you can't get consent to fit a new log burner unless it's replacing an existing one.)
We find the climate here to be a little warmer than Cambridge on average, with more very hot days. The main difference is the rainfall pattern; we get a lot of nice days with lots of solar gain; then when it rains, it really rains.
Building standards
NZ building standards aren't the same as those in Europe, so beware of making direct comparisons.
Recent builds are OK, but much of the housing stock was built in the 60s or 70s. They have timber frames, weatherboard or masonry cladding, and minimal insulation which leads to a certain degree of thermal transparency. Houses of that age were built with log burners or open fires; if the foundation is a concrete slab you might have electric underfloor heating too, but 50 year old technology isn't very good. European style central heating - wet or warm air - is pretty rare.
There is no mains gas where I live; bottled LPG is available but many folk do not bother as it's much more expensive than a mains supply. It's rarely used for heating; generally only cooking, and sometimes hot water. (Most houses have simple immersion cylinders for their hot water.)
Q. What is a heat pump in this context?
In NZ the term "heat pump" almost always means an air-sourced heat pump serving a single room.
There's an indoor unit, which may be wall or ceiling mounted; an outdoor unit; and a pipe containing refrigerant gas between them. Both units have heat exchangers and fans.
The standard install is "back-to-back", meaning a wall-mounted indoor unit with a minimal pipe run i.e. least hassle for the installers. There's a small raft of cheap self-employed installers who only really care about cheap, easy installs. You might liken them to trunk slammers.
Unless you're extremely price sensitive, it's worth finding a reputable installer who knows their stuff and will be likely to give you more options over where to site the outdoor unit.
Other options exist. You can get ducted heat pump systems that are akin to central heating, piping warm air around the house. You can get a multi-split system where one outdoor unit services multiple indoor units. However, these are both significantly more expensive to have installed. If we were starting out without any existing heat pumps in the house, we'd probably have one of these, but as it stands, adding three individual units worked out cheaper for us.
Ground sourced heat pumps also exist, but I have no knowledge of those beyond the fact that they're even more expensive (and mean digging up the garden to install), though they are reputed to perform better.
Q. What do your heat pumps do for you? Would a typical house have two or three of them, or just one in the main room?
Our house is a typical 1960s detached bungalow in suburbia. It's timber framed with masonry cladding.
We have double glazing (aluminium joinery, sadly); we had some good loft and under-floor insulation put in.
When we bought the house it had two heat pumps, one in each of the main living areas. That's the traditional school of thought here; you heat only the living areas, chuck extra blankets on the bed in the winter, and ignore the WHO guidelines about temperatures in sleeping areas.
Many Kiwis think a single air heat pump can replace a log burner as the sole heating solution for your house. Maybe that's reasonable on the North Island, but here in Christchurch that idea is frankly fanciful (multi-room systems excepted).
Being used to European style central heating, we weren't having that either. We added a heat pump in each bedroom, giving us one system in each room of the house (bathroom and utility excepted), and hence the ability to heat and cool on demand as we please.
In our experience, the warm air tends to stay in the room where it was warmed. Log burners are different, putting out a lot of radiant heat that heats the fabric of the house. (There's a secondary market here in heat recovery systems that take the hot air from the heated room and duct it to other rooms.)
I find a heat pump takes 20-30 minutes to heat a room. Smaller rooms are a little quicker, but of course your heat pump should be sized correctly for the job. Reputable installers will help you navigate the maze here.
My flat in Cambridge had gas warm air heating, and I find the heat pump performance similar. I haven't noticed the "pool of cold" phenomenon that I did with the gas warm air, though that may have been a symptom of the layout of that flat.
There is a drawback to air heat pumps. Ironically, they aren't as effective at heating in colder weather! Below about 4C outdoors, ours spend noticeably more time defrosting and less time heating. This does vary across make and model, so compare what's on offer with your climate.
We're talking mostly about heating here, but I should mention cooling as well. Kiwi heat pumps are really reverse-cycle air conditioners. We get a few really hot days each summer (30-35C, sometimes hotter) and we find them really worthwhile on those days. Whether this is an advantage where you live, I don't know.
Q. What do heat pumps cost to run?
The great benefit to heat pumps is that they are more than 100% efficient. This is because of how they work, which is by moving energy around as opposed to converting it. Typical figures are 3.5x efficiency, i.e. every kWh of electricity consumed puts 3.5 kWh of heat into the room.
Some people in NZ think heat pumps are very expensive to run. Well, they are if your expectations are unreasonable. They are not log burners! If you want to heat your whole house to 27C year-round, of course that's going to cost money. Be sensible, and the power bill will be sensible. (Consumer NZ have done the maths and reckon that the cost per kWh is only 10-20% more for heatpumps as compared with firewood, but of course the heat output profile is different.)
A tip: do not use a heat pump in "auto" mode, particularly during the day. The pump will switch between heating and cooling modes as the room temperature fluctuates. You should be selecting either heat or cool mode, with a reasonable thermostat setting.
Our cheapest month for electricity consumption tends to be Feb or March (late summer). The difference between then, and August (the teeth of winter), is about 400 kWh - NZ$100 or GBP 53 - per month. That difference will be almost entirely down to heating. This is for 2 reasonably frugal adults without special needs, in a 3 bedroom 1960s NZ house with double glazing and plausible insulation (and no gas bill).
Q. Do you find there is a problem with dust circulating? Are asthmatics happy with them?
We don't have a problem, though neither of us is asthmatic. The indoor units all have dust filters, which you're recommended to hoover from time to time (we do so monthly). We find the filter in the main bedroom traps the most dust, which doesn't surprise me. I understand there may also be a benefit for hayfever sufferers from the filters trapping pollen and spores.
Q. What are the noise levels like?
The indoor units, mostly a quiet whoosh though they do make a surprising range of creaks and flutterings at times. (We have stayed in places with horribly noisy air-con, but I think these were quite elderly systems.)
The outdoor units are comparable to the traffic noise from the busy road we live on. We have no issues with the noise disturbing the neighbours, but this is low-density suburban living on a bigger plot (800 m^2) than I was used to from the UK; your mileage may vary.
Q. How does the cooling mode compare with other forms of air conditioning?
This is quite a tough one to answer as we don't have much of a basis to compare against. All my life in the UK, I never lived anywhere with a cooling system.
A significant part of the cooling effect comes from air motion causing skin evaporation. So in many parts of the world maybe you can get away with ceiling or desk fans.
That said, we find that the ability to pre-cool a room before bedtime makes a big difference.
I've heard of "comfort cooling" systems, which bring ducted air from outside without any real cooling. I am unconvinced by these, though it maybe depends on the climate.
Q. What do you like about having heat pumps?
The ability to heat and cool only the rooms we want to.
Cooling!
Q. What do you not like?
They do take a few minutes to get going, but it's not really any worse than a wet central heating system.
They don't really heat the fabric of the house.
They lose efficiency below an ambient temperature of about 4C.
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