Jameshow
Established Member
Wood burner, gas and electric...I'm not putting all the eggs in one basket!
Boiler change!!
- Thread starter pip1954
- Start date
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This is what we opted for 6 years ago and it works very well. However it is getting very expensive to run and prices of pellets have gone from £300 per pallet last year to £395 and we get through 8 pallets per year. You also need plenty of space to store them and, unless you have a bulk hopper you have to manually load bags into the boiler hopper. Also the boilers are electro-mechanical so need servicing and ours has broken down once a year every year and always when you need it most!
HamsterJam
Let’s take it apart to see what’s inside….
Close but it is a refrigerant liquid rather than air that is compressed.
The refrigerant passes through an outside radiator with a fan to draw air over it. This warms the liquid (even in winter). which is then compressed to get the heat like you describe before passing through a heat exchanger to transfer the heat to the radiators/underfloor heating inside the house. The liquid is then allowed to expand, causing it to cool down then sent back to the radiator to warm up again. (If you stand in front of an ASHP, you can feel a cold blast.)
This describes a simple single stage system. There are more complicated systems including multi-stage systems and some with extra heaters.
Ground source or water source heat pumps replace the outside radiator with a heat exchanger to warm the refrigerant using pipes buried in the ground or water from a pond.
The GSHP units here are somewhere in the neighborhood of 30kw+ for larger houses, but they are drastically different than split type systems.
I don't know how the water heater tie-in works with them - if it's with the main unit or if the water tank itself is separate. if the water tank is separate, then it is probably very low output, maybe much lower than what you mention.
Typical electric resistive water heaters here are 4500 watts, large or small - no clue why. There are probably others that are not, but I have seen 80, 40, 30 in gallons - all the same size.
I don't have experience with the GSHP other than relatives, but I do have a split ASHP/AC combo and it's just super dandy. It's limited to 15k rated output - greater than that when the temp conditions are favorable, but that strangeness means the less you actually need the thing, the more output it has (and the more efficient it is).
Our heat is gas, and so is the water heater - cheap, crude and 40k btu and only 40 gallons. It recovers like a champ and runs even when there's no power. I love it.
Sounds like you planned to have both the GSHP and the oil burner running at the same time? I only run the GSHP. I keep the oil burner purely as backup.
It also sounds like your heating system runs at a higher temperature than the GSHP can achieve. This is critical. Our heating system runs at a maximum temperature of 55C which is (coincidentally) the maximum output temperature of our GSHP. I think that 55C max GSHP output temperature is typical. Many heating systems run the rads at higher temperature which is why a change to GSHP often needs morel and/or larger rads.
From memory we needed 400m of pipe but laid double that in case we needed to add a second GSHP. So we have 2 x 400m pipes running in the same trench. Flow and return are in the same trench so I guess the trench is 200m long.
I don't remember the exact depth of the trench. Maybe 1m. Not as deep as I expected, anyway. I may have a photo somewhere. I will check.
Yes, our ground is colder in the UK.
We’ve had a GSHP in and working for nearly 10 years, routinely serviced. No need to replace the propylene glycol solution in the ground loops. The service engineer just checks the concentration with a refractometer as part of the service.
A lot of myths around!
pip1954
Established Member
I seem to remember in UK we tend to lay the pipes in circles over lapping unless that is just to get more metres in a smaller place but someone who knows better may come along.
Yes, they haven’t had time to perfect heat pumps because they’ve only been out about 50 years!
Yes, often true I think. Coiled pipe need less land and less digging. Straight pipes get energy from a greater land area so less likely to drop the ground temperature and are more efficient. As we had the land we opted for straight pipes at the cost of more digging. Most of the digging cost was getting the JCB here in the first place so digging a longer trench was a small percentage cost increase, from what I remember.
Interesting statement regards the term 'carbon footprint' so felt I had to look into this further. Original source of the claim is this article which is an interesting read / perspective.
The article also highlights that the best thing we can do to minimise the effect of the current climate catastrophe is to vote for leaders who will among other things accelerate electrification.
" Voting for leaders who, among other things, have plans or strategies to slash the rampant flow of fossil fuels through the economy, mandate buildings that use less energy, and accelerate the electrification of America’s cars and trucks (transportation is the leading U.S. contributor of greenhouse gas emissions(opens in a new tab))."
Electrification of energy use, be it heating, industry demand or transportation is the smart move as every-time more renewable energy is added to the grid it can immediately offset carbon emissions from burning fossil fuels.
Fitz.
This is an interesting page regards the area you need, with some actual data which is nice.
There are two drivers on the area needed, firstly the heat transfer effectiveness into the pipes, you need enough pipe surface area to get the heat in, and secondly the heat transfer from the air/sun/surrounding earth to ensure you don't chill the earth by removing too much heat. In simple terms you need a long enough pipe spread out over a wide enough area. The coil approach is likely to be the optimum of pipe length vs ground area.
From your photos J4F I'd say your soil type is the at the dry, non cohesive end of the spectrum so you need lots of land area, most uk soils will be towards the other end of the table so suitable for coils in a smaller overall area.
My current combi boiler is 35kw but this is driven by the instant hot water demand for showering etc. Over the last 4 years my average daily energy used by the gas boiler has varied between 1.2kw in summer to 7kw in winter. To give me some leeway for a higher demand on individual cold days I think I would want a 12kW system, in the best case of getting 40w/m2 i need 300m2 of ground area, the total plot area for my property is 310m2, and the house covers a good portion of that, darn back to the drawing board.
F.
@Just4Fun Not as deep as I thought they would be. As @pip1954 said I have only seen coiled pipes and in a deeper trench; but then again I haven't looked that closely.
The comments about parts of the control panel on GSHP's blowing; a guy I used to work with had two systems with separate control panels and they both blew the same component within a week or two of each other. I can't remember what he said it was now and he had to wait a week or so for replacement parts and got a bit cold.
The comments about parts of the control panel on GSHP's blowing; a guy I used to work with had two systems with separate control panels and they both blew the same component within a week or two of each other. I can't remember what he said it was now and he had to wait a week or so for replacement parts and got a bit cold.
Ollie78
Established Member
I read through that, I actually heard it somewhere else on a YouTube video, perhaps that was there source.
Not sure I entirely agree about electrification being the answer, at least not if we don't get more efficient at it.
Every time we convert energy into electricity there is wastage, converting ac to dc there is wastage, batteries use vast amounts of resources to make etc.
Making solar and wind turbines similarly uses huge resources and the end of life products are not recyclable. Not to mention destructive to wildlife habitats.
I think using my 20 year old car and 50 year old petrol lawnmower is probably greener than buying a Tesla and a battery powered plastic robot mower.
I am all for trying to help the planet and try to reduce my waste, no more plastic shower gel, compost in the garden etc, etc.
However as a peasant there is no way I can afford new green electric cars and a new heat pump system anyway.
The carbon emissions offset is pretty interesting as well.
Farmers are being paid to grow specific crops ( some kind of enormous grass) that is really good at grabbing carbon from the air, companies can then buy credits in the sequestered carbon.
After its harvested it can be burned in power stations and is considered carbon neutral.
Ollie
I think the same, what is greener a car that is super clean but is scrap after 8 to 10 years or a more polluting one that last twenty years plus. Don't forget all the extra technology and complexity that makes the car super clean and has required vast amounts of energy to produce and resources it has consumed like Tantulum and other minerals.
John Brown
Freeloading Social media influenza
I don't think anybody is suggesting you should scrap your car and replace it with an EV(apart from the car companies), but maybe when you are in the market for a new car you consider an EV.
It's like replacing your old fridge with a new one, great from the manufacturer's point of view, fairly pointless in other respects.
It's like replacing your old fridge with a new one, great from the manufacturer's point of view, fairly pointless in other respects.
I got a free push mower off gumtree 15yrs ago when I had a small lawn in London. Now I have a larger lawn but I can still trim it with the push mower in 20mins so see no point changing it. Additionally I have the fun of lapping the cylinder blade each season and the snick, snick, snick of it afterwards.
Terry - Somerset
Established Member
GSHP needs far more than the postage stamp garden of the typical modern housing estate, and presents separate problems for flat dwellers where block heating would likely be the main option. It is a solution aimed at those with larger properties and land.
Wood pellets can deliver only a small part of total demand. "Crops" consume energy in transport and refining/conversion to electrical energy, and deny the use of land for food.
I question the logic of individual domestic installations as costs for equipment procurement, installation and maintenance are intuitively expected to be more expensive for multiple local systems, than a larger central capability.
It may suit government that individuals separately install generating capacity - PVs etc are a visible environmental statement. But insulating properties and fitting effective energy control systems needs local domestic action. Ultimately it must be better to reduce demand than build capacity to deliver unconstrained demand.
Wood pellets can deliver only a small part of total demand. "Crops" consume energy in transport and refining/conversion to electrical energy, and deny the use of land for food.
I question the logic of individual domestic installations as costs for equipment procurement, installation and maintenance are intuitively expected to be more expensive for multiple local systems, than a larger central capability.
It may suit government that individuals separately install generating capacity - PVs etc are a visible environmental statement. But insulating properties and fitting effective energy control systems needs local domestic action. Ultimately it must be better to reduce demand than build capacity to deliver unconstrained demand.
HamsterJam
Let’s take it apart to see what’s inside….
More likely not enough up take to make it worth while developing decent domestic systems. That of course is changing as we become more environmentally aware.
