Feasibility of Battery Backup/Generator for Boiler/CH/Hot Water etc

Bendy_House

Why would you want one that size? Just to have reserve power 'just in case'?

600W would theoretically draw 50A from your battery. Would there be a situation where you might do this?

molerat

Bendy_House said:

molerat said:

It is pretty straight forward to replace the FCU with a twin single back box, single DP switched  socket, 20A flex outlet plate. 3 pin plug fused as FCU and a bit of flex.

Why would you need all that? 

Surely just replace the FCU with a single socket with a DP switch. Boiler/CH cable terminated in a plug top. During power cut, unplug from socket, and plug into inverter.

Have I missed something?

All my wiring is TWE in the wall so that is what I would need to run it from a 3 pin plug.

Bendy_House

Cool.

From what I gather from Arfa's description of their setup, the CH is supplied via a FCU (when did they start calling these 'fused spurs' - that's all I see on Screwfix?). In which case, the simple, less-than-a £iver, option would be to replace this with a single DP socket and a plugtop.

The plug then just gets popped into the alternative supply when required, presumably via short extension cable to the new power source.

A thought, Arfa probably won't want too many car batteries inside the house :-)

Apodemus

Bendy_House said:

A thought, Arfa probably won't want too many car batteries inside the house :-)

…or a generator!

Mutton_Geoff

There has been mention of spikes damaging electronics here, but more importantly, it's the quality of the sine wave that will be more critical to the switched mode power supplies in modern electronics & controls. Cheap inverters and generators will struggle to power sophisticated electronics. Might run an old fashioned 60 watt light bulb but for decent conditioned mains substitute, you're looking at serious money.

grumbler

Mutton_Geoff said:
...it's the quality of the sine wave that will be more critical to the switched mode power supplies in modern electronics & controls. Cheap inverters and generators will struggle to power sophisticated electronics. Might run an old fashioned 60 watt light bulb but for decent conditioned mains substitute, you're looking at serious money.

 Any UPS has an inverter and is intended for electronic devices in the first place. And it's not 'serious money'.

Arfa__

Apodemus said:

Bendy_House said:

A thought, Arfa probably won't want too many car batteries inside the house :-)

…or a generator!

As it happens my boiler is located in the garage, so actually well placed for a bunch of batteries or running a lead under the garage door to a mini generator.

Sound it sounds like what might be best is a mini generator with a small online UPS plugged into it, so that I can guarantee it'll always be getting smooth power off the UPS battery, whilst the Geni keeps it charged up. The small UPS would then avoid any cut-outs when the Geni is off for re-fueling etc. The issue with a cheaper offline UPS, is it'll only switch the output to come from the batteries if there's any power cut-out, so i'm guessing it won't smooth out the Generators power so well.

Mutton_Geoff

grumbler said:

Mutton_Geoff said:
...it's the quality of the sine wave that will be more critical to the switched mode power supplies in modern electronics & controls. Cheap inverters and generators will struggle to power sophisticated electronics. Might run an old fashioned 60 watt light bulb but for decent conditioned mains substitute, you're looking at serious money.

 Any UPS has an inverter and is intended for electronic devices in the first place. And it's not 'serious money'.

I agree, but I was referring to stand alone inverters rather than an integrated UPS system which is designed for computer/electronic equipment. A "not serious money" UPS is usually designed for a short period to enable you to save/shut down in a power outage rather than sustained operation. Not suitable to power a heating pump/controller for longer than it would take the house to cool down after power failure.

ansaryon

FWIW, I tested using a bog-standard APC UPS (capable of providing 800W peak) with my old Glowworm boiler system a couple of years ago.

The good news is that it only drew 70W at most, including the pump running upstairs, meaning it could, in theory, run for at least an hour. 
The bad news is that the boiler wouldn't ignite, it went "click, click, click" but no flame was produced. It then had to be reset, only to fail again. Plugging it back into the mains - it fired up the second time (before the experiment it fired up first time, every time). From then on, it usually took two goes to fire up... could be coincidental, maybe not.

Searching online didn't give a definitive answer. Some mentioned that a pure sine wave UPS would be better (although TBH the boiler's fan and pump upstairs sounded fine), others said it's something to do with ground/earthing being out of spec when running from a UPS.

I wonder if anyone's actually managed it...

Bendy_House

ansaryon said:

FWIW, I tested using a bog-standard APC UPS (capable of providing 800W peak) with my old Glowworm boiler system a couple of years ago.

The good news is that it only drew 70W at most, including the pump running upstairs, meaning it could, in theory, run for at least an hour. 
The bad news is that the boiler wouldn't ignite, it went "click, click, click" but no flame was produced. It then had to be reset, only to fail again. Plugging it back into the mains - it fired up the second time (before the experiment it fired up first time, every time). From then on, it usually took two goes to fire up... could be coincidental, maybe not.

Searching online didn't give a definitive answer. Some mentioned that a pure sine wave UPS would be better (although TBH the boiler's fan and pump upstairs sounded fine), others said it's something to do with ground/earthing being out of spec when running from a UPS.

I wonder if anyone's actually managed it...

Interesting to have a real life example, Ansar. 

Any circumstances that may have caused this - extension cable used, or internal UPS power source a bit borderline? (What do they have inside them?)

It 'sounds' as tho' the supplied voltage was borderline, so possibly already delivering below a solid 230/240V. The additional draw from the gas valve (although that can't be much) brought it fractionally too low for the valve to engage.

Perhaps the valve was also getting a bit sticky?

Hard to think of an 'earthing' cause, or one that would CONTINUE to be an issue when full power was restored (unless pre-existing), but I don't know.