Anyone else had a bill for the recent cold snap?

[AGT]

I had an ex mod petrol generator that I sold a few years ago for a cheap inverter generator approx 1800watt output.
It was under £400 and works fine, mixed reviews on Amazon but that’s full of dafties trying to run 3 times the power off it, or starting it and then loading it immediately.

I worked with FG Wilson/Dieselec on many jobs and had lots of chats with fitters picking their brains, so I knew to run the generator off load to let it warm up before loading up and doing the same when turning off, I also turn the fuel off and then let it run the carburettor dry.

2 years in and it’s fine, not used much now, but kept topped up and run monthly

[Oldgreybeard]

I had an ex mod petrol generator that I sold a few years ago for a cheap inverter generator approx 1800watt output.
It was under £400 and works fine, mixed reviews on Amazon but that’s full of dafties trying to run 3 times the power off it, or starting it and then loading it immediately.

I worked with FG Wilson/Dieselec on many jobs and had lots of chats with fitters picking their brains, so I knew to run the generator off load to let it warm up before loading up and doing the same when turning off, I also turn the fuel off and then let it run the carburettor dry.

2 years in and it’s fine, not used much now, but kept topped up and run monthly

That sort of size and price would suit my needs OK. I need about 200W to meet the background loads, surging to about 800W when the water pump kicks on for a minute or two to recharge the accumulator. Needs a bit of thought as to how best to do it, but what would be ideal would be if the generator could run for a time to charge the batteries, then use the batteries to supply the peak loads that the generator couldn't supply.

The challenge is working out the best way to do that. One snag is that I can't predict when two pumps come on. The well pump draws about 600W, the treatment plant emptying pump is about the same. The latter only runs for about 20 seconds to empty the clarifying chamber, the well pump runs for around five minutes or so, usually. It's possible that both could come on at the same time, on top of the house base load of around 200W.

Ideally it would be useful to be able to run the heat pump as well, that draws around 1kW, and if it was on for 7 or 8 hours in every 24 hours than that should be enough to keep the house warm, even in very cold weather. If the generator was to charge the battery pack, then that would give us about 3kW to run the house during peak demand periods (say heat pump on, lights on, background load on and the water and treatment pumps pulsing on. I reckon something like that 1,800W genset would do the job. When the heat pump was off it could top the batteries back up at maybe 1,600W, and run the base load.

Just need to work out how on earth to arrange it. Might be better to look for a 48V DC generator, perhaps, and just charge the batteries directly.

[openspaceman]

With the amount of kit you have it looks logical first to get so the system will run off grid then find the most economical way to run a generator to charge the battery as you know the battery will run everything else for a while.

Air cooled generator sitting next to the A2A heat pump inlet may raise the COP a bit.

[Oldgreybeard]

With the amount of kit you have it looks logical first to get so the system will run off grid then find the most economical way to run a generator to charge the battery as you know the battery will run everything else for a while.

I wholeheartedly agree just need to find out a bit more about how to charge the battery safely from a generator. I've just found some German made ex-German army radio generators that might do the job. They look to be tough, and put out 50V DC, so might be OK for charging the batteries.

Air cooled generator sitting next to the A2A heat pump inlet may raise the COP a bit.

That ^^^ is an absolutely brilliant idea! Thanks very much indeed. It would make a very useful difference I'm sure, and recovering some of the waste heat from the generator like that would assuage my conscience a bit about needing to burn a bit of fossil fuel!

Might have a look at whether I could make that work a bit better by making an open enclosure that would allow the heat pump to draw air over the generator, to try and recover as much of the waste heat as possible.

[ALAN/ALAN D]

Diesel is the way to go.
Had a Yanmar EG55 for 20 years. 6.5 kW
Changed the internal start battery for a bigger one outside
with automatic charge cycle .

Never had a problem with it not starting.
Turn key or push button to start is the way to go.

Dooooo not go down the turn handle to start.

[Countrypaul]

With the amount of kit you have it looks logical first to get so the system will run off grid then find the most economical way to run a generator to charge the battery as you know the battery will run everything else for a while.

I wholeheartedly agree just need to find out a bit more about how to charge the battery safely from a generator. I've just found some German made ex-German army radio generators that might do the job. They look to be tough, and put out 50V DC, so might be OK for charging the batteries.

Air cooled generator sitting next to the A2A heat pump inlet may raise the COP a bit.

That ^^^ is an absolutely brilliant idea! Thanks very much indeed. It would make a very useful difference I'm sure, and recovering some of the waste heat from the generator like that would assuage my conscience a bit about needing to burn a bit of fossil fuel!

Might have a look at whether I could make that work a bit better by making an open enclosure that would allow the heat pump to draw air over the generator, to try and recover as much of the waste heat as possible.

Just remember if you allow the exhaust to go through the ashp you will rot it out very quickly, so you may need to consider extending the exhaust system. you could run the exhaust pipework in front of the ashp to recovr some of the "waste" heat, but you may need to deal with the rather acidic condensate.

I too have been looking at a generator for use in power cuts. I have a small petrol one, but make my own biodiesel so a diesel one would make much more sense,

[Oldgreybeard]

Diesel is the way to go.
Had a Yanmar EG55 for 20 years. 6.5 kW
Changed the internal start battery for a bigger one outside
with automatic charge cycle .

Never had a problem with it not starting.
Turn key or push button to start is the way to go.

Dooooo not go down the turn handle to start.

I'd much prefer a diesel, TBH, it's justifying the bigger price tag that's the concern. Bit of a dilemma, as I think if we had a power cut lasting several days in very cold weather then almost any price we could afford would be worth paying. If it turns out to sit unused for years then it will be a costly white elephant.

Just remember if you allow the exhaust to go through the ashp you will rot it out very quickly, so you may need to consider extending the exhaust system. you could run the exhaust pipework in front of the ashp to recovr some of the "waste" heat, but you may need to deal with the rather acidic condensate.

I too have been looking at a generator for use in power cuts. I have a small petrol one, but make my own biodiesel so a diesel one would make much more sense,

I like the idea of biodiesel, helped someone make some years ago. They used loads of it, along with lots of WVO. Does biodiesel store OK, do you know? I remember having problems with stuff growing inside a diesel tank years ago, some sort of bug that formed a sort of jelly.

Good point about the exhaust, too, I'd not thought of that. The heat exchanger looks to be thin aluminium, so most probably wouldn't take kindly to having acidic fumes blown over it. Seems a shame not to recover some of the waste heat, though, so perhaps just extending the exhaust might be the way to go.

We're probably taking this thread a bit off-topic now, though. I'll put my thinking hat on and may be start another thread about standby generation and ways of dealing with long power cuts in cold weather.

[openspaceman]

Good point about the exhaust, too, I'd not thought of that. The heat exchanger looks to be thin aluminium, so most probably wouldn't take kindly to having acidic fumes blown over it. Seems a shame not to recover some of the waste heat, though, so perhaps just extending the exhaust might be the way to go.

A bit of a non problem for the occasional power cut but easy enough to extend the exhaust into a coil and then vent it.

If this is an off grid thing then it makes sense to go watercooled with a watercooled exhaust.



I do remember seeing grills on natural gas flue outlets corroded into sharp spikes but not noticed it with stainless balanced flues.

[ALAN/ALAN D]

Ref “A bit of a non problem for the occasional power cut but easy enough to extend the exhaust into a coil and then vent it. “

With Diesel If you extract to much heat from the coil Sulfuric acid will condense in the coil. The temperature at the end must be above 138 Deg C.
For the occasional power cut I would stick with normal Diesel generator
I have converted petrol cars / lawn mowers / generators to propane. First car in 1970
Propane a lot more reliable than petrol. Leave it for years. Then go and start it.

[Fintray]

OGB, you need a 4 day power cut, as this certainly helped me focus on getting my back up generator back in working order (only been sitting in the garage for 25 years prior to that with my thoughts being that power cuts usually aren't very long!).

I couldn't afford the petrol to run mine for four days and last time I used it via the changeover switch neither the solar nor battery inverters recognised it.

Latest thought is to rectify the output and use it to charge the battery via an MPPT charger once I get enough pennies to have an inverter that will run islanded. That way it only needs to run a couple of hours a day.

Thankfully I've never had to run it for 4 days, I would normally just run it during the day and shut it off at bedtime, mine uses diesel at 1L/hr running the house. I didn't try my inverters during the power cut so I don't know if they would have worked or not though.