ASHP / backup generator

[Bozza]

Currently my wee Draper / toolstation back up generator runs some essential basics during power cuts at my house.  I’m looking at upgrading with a proper changeover switch and a bigger generator.  
 

There are plenty of guidance lists online with regards to the consumption of the usual domestic appliances, to allow me to estimate the correct capacity generator I require. 
 

The bit I need help with is - How is the best way to figure out the consumption of my ASHP, to see if it’s viable to have it running off a back up genny.  Appreciate its consumption will relate to variable outdoor temperatures etc.  I’m a bit of a biff when it comes to watts, kWh, and such calculations and can’t seem to get an answer anywhere else online.

 

cheers Bozza

 

 

 

 

[joth]

24 minutes ago, Bozza said:

Currently my wee Draper / toolstation back up generator runs some essential basics during power cuts at my house.  I’m looking at upgrading with a proper changeover switch and a bigger generator.  
 

There are plenty of guidance lists online with regards to the consumption of the usual domestic appliances, to allow me to estimate the correct capacity generator I require. 
 

The bit I need help with is - How is the best way to figure out the consumption of my ASHP, to see if it’s viable to have it running off a back up genny.  Appreciate its consumption will relate to variable outdoor temperatures etc.  I’m a bit of a biff when it comes to watts, kWh, and such calculations and can’t seem to get an answer anywhere else online.

 

cheers Bozza

 

 

 

 

Most ASHP will have a number for max or startup current (in amps). That will be the number you need to look most carefully at, as a small gennie may struggle to respond to the sudden load. 

It'd be interesting if a small couple kWh battery could work well to reinforce a generator to cover odd peaks. Obviously if you have solar PV the battery comes into its own for this use case 

[Bozza]

Thanks @joth  have attached the label for the pump how do I interpret these numbers in relation to what you’re advising, it’s all gobledegook to my brain.

 

 

[markc]

Unfortunately small genies are a nightmare to spec.  We have a lot of machines with 2.2kw single phase motors that will start and run happily on a 13amp plug. We have a old heavy Haverhill 5kva generator that has no problem at all running these machines but a new 10kva won’t because the voltage drop on start up causes our machine to shut down.

[sharpener]

It looks as though the 28A starting current would need as a bare minimum a 6kW genny and as @markc says they are notoriously difficult to size correctly. Modern inverter based gennys are more economical at part-load but have all sorts of protection in them which may trip.

 

Suggest you hire one for the weekend and if successful buy the exact same model.

 

Does your HP have a quiet mode or night mode which might draw less current?

 

Another old trick is to get a biggish induction motor and run that in parallel. Start that first with a star-delta starter, then its rotating mass will help supply the HP on startup. But this would require intervention every time and is not easy to automate.

 

[JohnMo]

I use one of these, induction hob, oven, lights tv at same time no problem. Our 6kW ASHP no issue.  But your heat pump is bigger so idea.

 

https://hyundaipowerequipment.co.uk/p1pe-p10000le-7-9kw-9-8kva-recoil-electric-start-site-petrol-generator-powered-by-hyundai?gclid=CjwKCAjw69moBhBgEiwAUFCx2Fbz7H-U8e087ep8aNj5WsMWeXQBVip-bHh7G5iLfnaQfHVlSxUlphoCSAQQAvD_BwE

[sharpener]

Remote start might be useful but it hardly seems worth paying twice the price https://hyundaipowerequipment.co.uk/hyundai-hy6500sei-petrol-inverter-generator-6500w-pure-sine-wave.

 

However it is also a good bit quieter.

[TonyT]

Use a switchbot for remote switching!!

 

[TonyT]

I’d go with the hiring of the unit first as posted earlier, as starting currents on generators can be a funny thing.

 

as always start the generator, let it get warmed up and then apply load, too many dafties, turn generator on, then apply full load and it dies… they then give negative Amazon reviews due to the lack of brain cells/ not reading manufacturer instructions 

 

[Bozza]

Thanks for comments & input folks.  Managed to get someone to figure out how big a generator I’d need.  

[sharpener]

@Bozza what did they say?