Discussion in 'Engineers' Talk' started by jimbobby, Oct 4, 2021.

  1. jimbobby

    jimbobby Screwfix Select

    With rising gas electric prices....and at current diesel/petrol prices, would it be more economical to use a genny to provide pure heating to a home.
    (just a pure heat source,)
    Say taking cost of genny over 5 years.
    Any informed opinions
  2. Air source heat pump + government grant.
  3. FlyByNight

    FlyByNight Screwfix Select

    Unlikely as you will be paying more for the fuel to start, then efficiency will come into play.
  4. Bob Rathbone

    Bob Rathbone Screwfix Select

    The generator route will only pay if you can use both the electricity and heat (Co generation). A diesel engine running on heating oil or red diesel will be fairly economical but will have noise maintenance issues, better to use a spark ignition engine running on natural gas. It will be clean and quiet. As a footnote, expect to get 3 times the heat than electricity, ie a 3 kW genny will produce 9kW of heat. Use a genny that runs at 1500 rev min for longer life, less maintenance and vibration.
  5. jimbobby

    jimbobby Screwfix Select

  6. MGW

    MGW Screwfix Select

    With the Wispergen which is an external combustion engine sound is not so much a problem, there was at one point a gas boiler with a sterling engine built it, there is not reason why a engine should not power a heat pump directly, to generate electric to be fed into a heat pump seems better option.

    But for any heating system we are looking at a compromise between cost of installation and running cost. My brother-in-laws old house had a heat store in centre of house and solid fuel, solar and LPG all able to feed in, it worked well, when he was in Germany visiting daughters the house could be maintained at a back ground heat of 10ºC using just the electric unused solar power, and the geofencing could get house to 20ºC on his return with the stored energy, when at home lighting the wood burner in the evening was enough of a boost to maintain house at 20ºC and LPG boiler rarely used, it seemed an ideal system.

    However when he moved he looked into having same system in new house, but to install would cost £20,000, at that even if he lives to 100 he would not get the investment back. And it puts very little extra value on the house.

    I would say with this house heating costs around £600 per year, however much is done to reduce the cost other than solar or wind, the lowest one can possible expect to pay is £500 so looking at saving no more than £100 a year and that is unlikely, at 70 it is unlikely at 95 I am still living at home, so 25 years maximum. And 25 years is also about the limit where money borrowed with interest can be worth while. So £2,500 is the maximum it is worth spending so this limits what is worth while.

    My heating costs with oil are less than heating costs when I used gas, but oil boiler around £2,500 and gas boiler £800 so if we had gas we would use gas, but not willing to have a potential bomb in my back garden so LPG no thanks.
  7. skydelph

    skydelph New Member

    Depending on your annual outside temperature, air heat pump might be effective (unless you will need to use backup a lot).
  8. Bob Rathbone

    Bob Rathbone Screwfix Select

    Cost is always an issue that tends to kill off most peoples dreams of improving their energy efficiency. We have seen over the past 15 years, continual legislation from Government and regulation from energy suppliers that require the installers of Co Generation and solar etc, to be registered within an MCS scheme, also a Part 'P' scheme and maybe even Gas Safe. All of this regulation requires the installer to pay a fee to a body to be allowed to do this work. Ultimately, it is the customer that must pay this fee in the charges made by the installer, it is one of the installer's costs that has to be recovered. Installing 'Green Energy' is not magic, it requires no extra skills, just follow the manufacturers instructions and the trade you learned as an electrician or plumber.
    skydelph likes this.
  9. MGW

    MGW Screwfix Select

    I find that interesting, I remember our refrigeration wagons with both a diesel and electric motors, I assume the electric was so noise reduced.
    skydelph likes this.
  10. skydelph

    skydelph New Member

    Energy is not a magic in any physical, technological, fees and regulatory terms.
    Diesel is temperature dependent as well, 'electricity' is always the point of the energy source :)
  11. MGW

    MGW Screwfix Select

    I have seen so many methods used, in the Falklands when building mount pleasant air port we used simple convector heaters, but for the permanent structure the waste heat from the main generators was used then boosted to heat the complex, but you are looking at a complex designed from day one to do this, to convert an existing building is very different to designing from scratch.

    And this is the route of the problem, heat pumps are good, the main advantage is they can both heat and cool, but to heat you want the heat exchanger low, and to cool you want it high, so to do both only option is fan assisted radiators. And these are not cheap.
  12. quasar9

    quasar9 Screwfix Select

    Combined heat and power is nothing new and it’s efficient. ! But it’s now in the “discredited” pile simply because it uses fossil fuel. Even if it ran on gas it would not be acceptable to the green brigade unless it ran off bio methane. But a modern IC engine is as complex as a heat pump and worse needs far more frequent servicing to change oil, filters, spark plugs etc. You just can’t win !

    as I see, nuclear is our only real option. Here there is some good news, Bill & Melinda Gates foundation have been researching on reactors that can run off spent nuclear fuel and the results are very encouraging. This is better than the RR mini nuclear reactors, which a massively cheaper than the conventional types but still require the same enriched fuel levels.
  13. JohnMorgan10

    JohnMorgan10 New Member

    If you can install it yourself and don’t mind the initial outlay, then a wood stove might be an idea - they’re quite nice too.

    They are expensive to install, but once done you’ve got it forever. Wood is fairly cheap to purchase and stockpile if you have a shed or garage.
  14. quasar9

    quasar9 Screwfix Select

    Great idea, but already many cities or boroughs within cities have or bringing in soon, restrictions that limits you to types of wood and it’s moisture content.
  15. MGW

    MGW Screwfix Select

    The clean air act 2019 has already made some changes, it started in 1956 and I remember smog. I can remember riding a scooter from Warrington guiding my father following me in a car, as he could not see the road, so I must have been at least 17 so around 1968 we still had smog.

    At that time we did not in general understand the need for after burn, fires like this wallnoefer.PNG can today stop most of the particular emissions, but they have a flaw, they rely on electric to work fans etc. This one Hughes Condensing Stove 2 small.jpg even worse, with gas or liquid fuel easy enough to arrange it so power failure auto turns off the heater, not so easy with solid fuel.

    There have been attempts, rocket-mass-heater-diagram.png this rocket mass heater is one of the few condensing heaters using solid fuel, however in the main they are home made, and insurance is the problem. Wood pellets seem to be the way forward, it allows more control including fail safe, but in the main people burning wood use methods to get the fuel which are not so good Man_rummaging_thought_a_skip.jpg be it old pallets or fibre board the problem is paint and glue used, plus can you identify rhododendron wood or laburnum, as a bush or tree maybe, but once cut down one has no idea what wood your burning.

    Wood and coal in general have the same energy per unit weight, however it is the volume which is important when designing a burner, so a fire designed for soft wood is not good with hard wood, and the reverse is also true, this is why you hear conflicting reports about best wood for burning, it depends what the unit was designed to burn.

    Even coal has the same problem, the Tornado was designed to burn poor coal, not a good railway engine to take pictures of, as it has very little smoke and steam around it unless set up for photo session.

    One of the narrow gauge railways was having problems setting alight line side grass, and tried moving to using oil fired boilers which also had the advantage of less training for the fire person. However oil costs and other considerations resulted in this being short lived, and they are back to burning coal.

    Narrow gauge engines were often designed for non UK use, and many needed modifying to use UK fuels. Where the fire is so important as with steam engines we have learnt how to modify fire boxes to suit the fuel, but with domestic fires in the main they are to look nice on Christmas day, or for emergency use, I have never lit a fire in my open grate.

    However there are gas boilers with Sterling engines built in [​IMG]the Baxi-Ecogen mCHP boiler is shown. Although most are much larger upload_2021-12-31_16-22-25.png and mainly for industrial use.
  16. quasar9

    quasar9 Screwfix Select

    Significant Increase complexity to make a marginal improvement as in the case of Sterling engine boilers

    This reminds me of the general move to lean burn engines in the 80’s, mainly driven by the need to reduce hydrocarbon emissions.

    Prior to that most petrol engines were marginally over fuelled even when running with the choke off. Technically they aimed for the correct stoichiometric mix of fuel and oxygen but carburettor technology meant they erred towards the excess.

    Lean burn bought it’s own set of problems. They ran hot. So
    The cooling system had to be uprated.
    The valves and the spark plug had to be made to withstand high flame temperature.
    The oil modified to cope with higher cylinder temperatures and not carbonise.
    The carburettor had to go and fuel injection introduced.
    It also bought in the ECU and a raft of sensors.

    the side effect of higher temperature, nitrogen reacts to form NOX or oxides of nitrogen. Solution to this more technology in form of EGR systems and valves.

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