Altering Central heating wiring Connections

[coshhassessor]

Scenario: frequent, regular, long lasting powercuts in the winter leave me without central heating (and since I only have central heating, by default I am totally without heating ).

Suggestion: buy a generator, and replace the FCU at the boiler clock with a plug and socket, such that the control side is the plug and can be plugged into the output from the genny, thus providing electrical power so the heating can run.

Question: is this feasible ( the suggestion was made by a heating engineer)? Knowing what's inside that FCU (i.e. 2.5mm2 T&E going in and out), this seems to be Bad Idea.

If it isn't feasible, are there any other (sensible, polite, logical) suggestions, as listening to the kids crying when they're cold is not an experience I relish

COSHH

 

[andy]

what might be cheaper is gettin a computer UPS. wire the boiler to the UPS. job done. on most, you can easily add a few more batteries.

altho if you still want the generator, best solution is to wire it to the boiler via a 2NO2NC contactor (this will make sure that the generator power cannot go back and fry the bloke repairing the cables etc)

or, put a plug and some flex to a nearby socket to power the heating. in power loss, plug into genny

 

[plugwash]

anyone measured how much a typical CH system draws from the leccy supply. Fitting the system with a suitable plug and pluging it into a UPS could be very workable and if the drain is low it could last a while even without extra batteries. However you should note that some ups units especially smaller ones have warnings against plugging in motor driven appliances.

 

[andy]

anyone measured how much a typical CH system draws from the leccy supply. Fitting the system with a suitable plug and pluging it into a UPS could be very workable and if the drain is low it could last a while even without extra batteries. However you should note that some ups units especially smaller ones have warnings against plugging in motor driven appliances.

i would imagine that the pump uses most of the power. never actually tried it myself

 

[Steve]

for what its worth, we have a UPS at work, it powers 3 tills and a computer (0.8kw?), when the power goes off it lasts about 15 mins, enough to serve the last few customers in the dark

The concern with motor driven items i guess would be 1. startup current and 2. wear on the UPS electronics that smooth out the 50Hz phase.

How much current does a CH pump draw? 100w max? UPS might last an hour, maybe a bit more, then what are you going to do for heating (original poster referred to long lasting power cuts)

 

[andy]

for what its worth, we have a UPS at work, it powers 3 tills and a computer (0.8kw?), when the power goes off it lasts about 15 mins, enough to serve the last few customers in the dark

The concern with motor driven items i guess would be 1. startup current and 2. wear on the UPS electronics that smooth out the 50Hz phase.

How much current does a CH pump draw? 100w max? UPS might last an hour, maybe a bit more, then what are you going to do for heating (original poster referred to long lasting power cuts)

get a few extra batteries. i have over 200AH of battery power on mine. can take my comp on full load (comp, 2 TFT's, speakers, modem, router, cordless phone) for over 6 hours...itll take a combi boiler for days!

 

[baldelectrician]

see nothing wrong with your post, assuming the fcu is the only supply to the heating circuit.

i would use a flex rather than a cable to supply timeclock / boiler.
Would look a bit naff- that doesn't matter if youre warm



central heating has a 3 amp fuse usually and the load is mostly less than 1 amp

 

[slippyr4]

would there be any earthing issues? Gennies are IT supplies normally aren't they? and CH stuff needs proper earthing.

Just adding a thought to the debate, i don't know the answer to that.

 

[ChrisR]

I'd use the £30 inverter from my Tranny and one its batteries. That would keep the htg going for several hours. Just connect the CH on a plug and socket. OK I'm cheap!

 

[ban-all-sheds]

Does your inverter produce a proper sinewave, or some nasty waveform which might b*gger the pump motor?

 

[ChrisR]

It's pretty horrible I put a scope on it, more like an earthquake on a seismograph. The pump might get a bit hot - turn the boiler stat down a bit? Dodgy pumps blow Potterton pcb's as it is so they might be a weak point!

 

[securespark]

Yes, CH systems never have more than a 3A fuse. They may only run around an amp, but there will be surges when the pump kicks in.

 

[ChrisR]

Just checked 5 combis (including pumps therefore) nothing over 186 watts.

 

[securespark]

Is that value when the pumps are starting up or running?

When motors start up, there is often quite a large surge.