3 phase boiler install on domestic property

[Edders]

Hi all,

A customer is looking into the option of upgrading to a 3 phase power supply in order to get a new electric boiler system installed. They currently have a single-phase supply. They have an out-building with an electric car charger. Would an option be to have say a 1 way 3 phase board next to the main cut-out fuses and then have one of the phases supplying the out-building, one supplying the main consumer's unit and the 3rd phase supplying the boiler? Or would the main CU need to be split amongst the phases? I think from memory its at least a 10 way board. The main draw in the house is an electric shower. Thanks for taking the time to read.

 

[i=p/u]

Single phase to 3 phase converters??? , what's the boiler spec.

 

[snowhead]

Is the boiler single phase or 3 phase?

 

[telectrix]

i would be inclined to get customer to buy a 3 phase boiler. last one i did would have been 63A on single phase, but was only 21A on 3 phase. that meant the cable feed to the boiler was 2.5mm as opposed to 10.0mm. then in your case, i'd maybe have 1 phase for the house and outbiulding and 1 phase for the charger.

 

[Edders]

Single phase to 3 phase converters , what's the boiler spec.

Single phase to 3 phase converters , what's the boiler spec.

Dont have the spec yet, its all just an idea at the moment. Its a massive house so I think its going to be a big boiler. They have been advised by the boiler people that it will need to be 3 phase.

 

[telectrix]

They have been advised by the boiler people that it will need to be 3 phase.

"boiler people" with common sense. that's got to be a first. can't be BG then? ??

 

[i=p/u]

Well your next step is finding out the rating plate I'd say?

 

[Edders]

i would be inclined to get customer to buy a 3 phase boiler. last one i did would have been 63A on single phase, but was only 21A on 3 phase. that meant the cable feed to the boiler was 2.5mm as opposed to 10.0mm. then in your case, i'd maybe have 1 phase for the house and outbiulding and 1 phase for the charger

Thanks, my concern was the balancing of the loads, as the car charger will only be on every now and again, in the evening.

 

[Marvo]

I'm not sure about the UK regs but where I am the main DB or CU must have a single point of isolation for the entire electrical installation including all final circuits and sub-DB's etc. Hence the main CU would need to be 3-phase if the incoming supply is 3-phase.

I'd get the exact make and model number of the boiler and download the spec sheet. Often 3-phase boilers can be wired as single phase using the internal wiring option links. The current for the boiler configured as single phase might be too high however.

 

[Edders]

I'm not sure about the UK regs but where I am the main DB or CU must have a single point of isolation for the entire electrical installation including all final circuits and sub-DB's etc. Hence the main CU would need to be 3-phase if the incoming supply is 3-phase.

I'd get the exact make and model number of the boiler and download the spec sheet. Often 3-phase boilers can be wired as single phase using the internal wiring option links. The current for the boiler configured as single phase might be too high however.

Yes same here, needs to have a single point of isolation. I'm guessing that to run most efficiently that 3 phase would be best?

 

[Darkwood]

If they are going down the route of an electric boiler I would look into considering air source heating, in recent yrs it has developed enough to become more viable in the UK, I know 2 houses running it and it was -2 c outside and it had no problem heating the house and water up without tapping into its booster elements, given that your already planning on heating by electric it would be crazy not to use a system that can do the same job at a fraction of the billing costs.

 

[Edders]

If they are going down the route of an electric boiler I would look into considering air source heating, in recent yrs it has developed enough to become more viable in the UK, I know 2 houses running it and it was -2 c outside and it had no problem heating the house and water up without tapping into its booster elements, given that your already planning on heating by electric it would be crazy not to use a system that can do the same job at a fraction of the billing costs.

Yes, certainly worth considering. I don't really know much about them, can the existing heating system be incorporated into it or is it a case of ripping it out and starting again?

 

[Darkwood]

You would have to consult a supplier on that but as I understand it can be used on most household plumbing installs, radiators, underfloor piping etc, I cannot see why it cannot be adapted to an existing system, the two I was involved with were fully new installs including pipework but were new builds, I believe the crucial factor to viability of such systems is the energy efficiency of the building so it may not be suitable for older buildings, that you would have to discuss with the company who would supply the system.

 

[Edders]

Well your next step is finding out the rating plate I'd say?

Just trying to get an idea of the options that I can offer the client. My concern would be balancing the loads across the phases. I don't do a huge amount of 3 phase stuff so not 100% sure on the best route.

 

[Edders]

You would have to consult a supplier on that but as I understand it can be used on most household plumbing installs, radiators, underfloor piping etc, I cannot see why it cannot be adapted to an existing system, the two I was involved with were fully new installs including pipework but were new builds, I believe the crucial factor to viability of such systems is the energy efficiency of the building so it may not be suitable for older buildings, that you would have to discuss with the company who would supply the system.

ok thanks.

 

[Marvo]

With domestic 3-phase it's more about distributing the individual loads as evenly as possible across the phases, not actually achieving a constant balanced load.

 

[Edders]

With domestic 3-phase it's more about distributing the individual loads as evenly as possible across the phases, not actually achieving a constant balanced load.

So it wouldn't be an issue having say the main CU on one phase, the car charger on one and the boiler on a 3 phase ?

 

[telectrix]

So it wouldn't be an issue having say the main CU on one phase, the car charger on one and the boiler on a 3 phase ?

you can only go so far with balancing the loads. the 3 phase boiler, a largish load, is balanced anyway. you then juggle the rest to estimate the best way to get close to balance.

 

[Edders]

you can only go so far with balancing the loads. the 3 phase boiler, a largish load, is balanced anyway. you then juggle the rest to estimate the best way to get close to balance.

Thanks telectrix, what im trying to avoid is taking apart the main CU and splitting it up.

 

[telectrix]

so put the main CU on 1 phase, then maybe the outhouse and charger on another. then you have a spare phase to play with if loads are unbalabnced. e.g split the charger from the outhouse.