LPG Generators for residential use

frank joyce · Dec 6, 2021

What with everything thats going on at present and likely to continue well according to the Business Secretary thinking of getting above. Like the look of Pramac GA20000 20KVA 3 Phase LPG Residential Backup Generator. anyone had experience of these or LPG generators in general. unsure of my facts but seem to remember reading that electricians are qualified 1, 2 or 3 grades the last being the most qualified! Unsure what grade to ask for. Not sure if go for an install with an independent electrician or one that the generator supplier sends round! feel sorry for the folk in the NE and Scotland as well remember during the Great Storm of 1987 here in sticks in Hampshire, no electric or water for 2-3 weeks.
many thanks

Sparkgap · Dec 6, 2021

How are you looking to control it? I assume you already have a 3phase incoming supply so will it be manual start with a manual changeover or automatic start/changeover on loss of supply/phase?

MJPD29 · Dec 6, 2021

Never heard of a grade 1 2 3 electrician? Is that something only in Scotland or wherever you are? I've never even heard it mentioned before.

James · Dec 6, 2021

wow, 7 to 10 litres per hour of Lpg
£5 to £7 per hour running costs. (on LPG)

similar diesel generator 4 to 6L per hour £2.80 to £4.20 per hour

the only time i think the gas powered generators are worth considering is when they are run from mains gas, not bottled gas.
this means you dont have to store any fuel.
the downside is that the gas supply may be cut off if there is a natural disaster and that is the time you may need it most.

einhorn · Dec 7, 2021

James said:
wow, 7 to 10 litres per hour of Lpg
£5 to £7 per hour running costs. (on LPG)

similar diesel generator 4 to 6L per hour £2.80 to £4.20 per hour

the only time i think the gas powered generators are worth considering is when they are run from mains gas, not bottled gas.
this means you dont have to store any fuel.
the downside is that the gas supply may be cut off if there is a natural disaster and that is the time you may need it most.

einhorn · Dec 7, 2021

not sure i have this right, bit of a greenhorn. wrote re LPG generator. as you say WOW, hadnt realised running costs that much on bottled gas. re 3 phase no idea but generator outside abutts garage with all the electrics inside. spoke to neighbour and he said that minimum size he would look at is 5000KV so perhaps 20000 too big. you can see why i need a good electrician preferably one used to fitting generators. do i go with a total install job from generator firm or get it wired up by own electrician? Annoying thing is heating oil tank stands pretty close to where generator will live but as far as i know there are no specific generators which will run off this without beggering up the engine. yes diesel and do run a diesel lawnmower but only have storage at present for 20 litres so wont last long. wonder if one can order diesel, perhaps red! to be delivered like heating oil but would need getting a storage tank. lots of decisions. cheers

pc1966 · Dec 7, 2021

Backup power is a lot more cost and trouble to do than you initially think. There are lots of decisions about what you could do and of course the cost and possible planning permissions aspects to what it is practical to do. Generally speaking you should speak to a commercial/industrial electrician who has some experience of this (e.g. quite a few farms need backup power, etc) as the bottom run of "domestic installer" generally won't have the knowledge or experience in this area. Off the top of my head you need to consider:

What is on backup power, your whole home/business, or just critical circuits?
Do you also need UPS for a no-break changeover (e.g. for computer systems, etc) or can you tolerate a few minutes to hours for change over to backup?
Asa above, do you need an automatic transfer switch arrangement (detects loss of phase power, starts generator, switches over) or are you OK with doing it manually when you realise the power ain't coming back on soon?
Form 1st point, how big a generator and single or 3-phase?
How much autonomy (run-time) do you need?
Do you need a fuel store if a tank-full is not enough?
What kind of fuel?
Do you need that to be plumbed in (i.e. external tank to generator's capacity) or can you tolerate stopping the generator to refuel?
If you are looking at fuel storage be aware there are lots of regulations around this, not just the fire risk but also ground contamination due to spillage.
Fuel life in the tank. Have you means to cycle it so not too old.
Noise levels? The better generators on part-load are usually tolerable, some can be incessantly noisy.
Monitoring, if critical how will you know (perhaps remotely) that it is on-generator, and when the fuel is due to run out?
Means of earthing? Under loss of supply conditions you cannot assume the supply earth is still present, so your generator will need to work with an earth rod, etc.
Testing. If you don't regularly test the generator under realistic conditions then when you really need it it won't work.
Security, they are very appealing to professional thieves.

I'm sure some of the folks on here will know more and add to this list of points.

For many homes just getting the lights and boiler on power would be a big improvement, but the safety and operational practicality of that needs careful thought and safe implementation.

brianmoooore · Dec 7, 2021

James said:
wow, 7 to 10 litres per hour of Lpg
£5 to £7 per hour running costs. (on LPG)

similar diesel generator 4 to 6L per hour £2.80 to £4.20 per hour

These figures are a little misleading, in that they are best case for diesel price, and worst case for LPG.
LPG in portable cylinders is that kind of price, but bulk prices into a fixed tank are cheaper. I bought LPG for 55p/l a couple of months ago, which gives the LPG costs as £2.75 to £5.50 per hour.
The diesel costs assumes that red diesel is available, which was around 60p/l + VAT = 72p/l, but is considerably higher now.
At 72p/l, diesel costs are £2.88 to £4.32 per hour.
If the genny has to be run on white diesel, at £1.40/l ? , the diesel costs go up to £5.60 to £8.40 per hour.

James · Dec 7, 2021

brianmoooore said:
These figures are a little misleading, in that they are best case for diesel price, and worst case for LPG.
LPG in portable cylinders is that kind of price, but bulk prices into a fixed tank are cheaper. I bought LPG for 55p/l a couple of months ago, which gives the LPG costs as £2.75 to £5.50 per hour.
The diesel costs assumes that red diesel is available, which was around 60p/l + VAT = 72p/l, but is considerably higher now.
At 72p/l, diesel costs are £2.88 to £4.32 per hour.
If the genny has to be run on white diesel, at £1.40/l ? , the diesel costs go up to £5.60 to £8.40 per hour.

it was not supposed to be misleading, i simply googled lpg price uk and i think it was 70p yesterday
red diesel prices were almost the same at around 70p

brianmoooore · Dec 7, 2021

You'll struggle to buy cherry for anything like 70p, including VAT, at the moment, and the LPG price you've posted is for Autogas. The price of the latter varies wildly across the country, depending to a large degree on local competition. It costs me £27.50 to fill my car at Bristol; £40.00 at my local BP.