Replacing a gas boiler with electric.

[Soulsurfer]

Hi just after a bit of help ref a swap out as above for one of my builders at his home,
He wants to replace gas boiler with an EHC 9kW Comet/Fusion boiler and has been quoted to have necessary 10mm T & E run from new meter to boiler position which is around a metre away.

Thing is I don't have much experience as yet with boiler controls although following S plan or similar is fine but this is on a tariff which is 20 hrs in 24 off peak rate and 4 hours on full rate in 2 x 2 hr bursts.

They have quoted to fit a Danfoss 103-E7 7 day timer which I expect would be fitted in cupboard where boiler is as there is a programmer in there now existing for gas boiler.

There is a normal room stat on wall in hallway too so I'm thinking it's just a case of rewiring the stat and new programmer to the elec boiler as required plus feeding the programmer via a 3A fused SFCU.

would it be best to run the 10mm feed through a DP switch isolator in cupboard next to boiler ? or direct in ? as it looks like the DNO wants a 4 pole switch fitting for the on and off peak supplies after the meter and then 2x 63A mcbs usually out when general service and off peak consumer units are used.

Although as heating only there is not likely a need for extra consumer unit such as with storage heaters in this case.

Any advice appreciated, Thanks

 

[Leesparkykent]

Is he on mains gas?

 

[Soulsurfer]

Is he on mains gas?

Yes mate he is but due to cost wants to convert to totally electric

 

[Leesparkykent]

Yes mate he is but due to cost wants to convert to totally electric

He must be mental ....The electric boiler will cost him more to run without a doubt.

 

[Soulsurfer]

He must be mental ....The electric boiler will cost him more to run without a doubt.

He's been convinced by DNO that it's cheaper & 100% efficient and cost effective as their contracting business side outlet has quoted the install !

 

[ImpededLoop]

A freestanding convector heater from the DIY shop is also 100% efficient.

Have you explained that it'll cost more to run than gas? Also, he might find the lights dim every time it cuts in depending on how good the dno network is.

 

[Last plumber]

If he's changing that solely for saving money, I'd advise him to look into it further first.
( out of curiosity, is the home fairly small ? it's only just over 30700 Btu/hr) What type of hot water system has he got ?

 

[Leesparkykent]

Yeah 100% efficient but I still cant see how it will be cheaper to run Even the sales gumpf says ideal for replacing LPG or oil. The control Side of things....The boiler has a built in pump and the control connections R and P are Volt free so do not follow a conventional S-Plan diagram other wise your supply 240V to the boiler PCB and damage it. You will have to feed grey of both valves from R in boiler and connect oranges of both valves to P in boiler. This way the volt free switching is switched from the micro switch in the valves... When the micro switched is closed by the room or cylinder thermostat calling for heat, 240V will be supplied to brown of either valve depending on what's been called for, the valve will motor round and close the switch between grey and orange.

 

[Wilko]

On the efficiency side, looking at BG just now they have gas at 3.6p per kWh and elec at 12p. Electric more efficient? Not so much anymore with modern condensing boilers claiming 90% efficiency and internal voltage drop of say 3% there's only 7% difference. Adjusting for boiler efficiency that's 4p for gas. Forget the voltage drop and use the cheapest night rate of 6.5p for leccie and for the same heating I'm expecting him to pay 50% more at least. What have I missed ?

 

[Resu]

Is there an electric shower in the property? If so might have to think about a relay too.

 

[Soulsurfer]

Yeah 100% efficient but I still cant see how it will be cheaper to run Even the sales gumpf says ideal for replacing LPG or oil. The control Side of things....The boiler has a built in pump and the control connections R and P are Volt free so do not follow a conventional S-Plan diagram other wise your supply 240V to the boiler PCB and damage it. You will have to feed grey of both valves from R in boiler and connect oranges of both valves to P in boiler. This way the volt free switching is switched from the micro switch in the valves... When the micro switched is closed by the room or cylinder thermostat calling for heat, 240V will be supplied to brown of either valve depending on what's been called for, the valve will motor round and close the switch between grey and orange.

Thanks Lee, and in reply to others who have also provided help & advice on this... yes I did say it would likely cost more to run but he said gas is costing £280 / month on DD and it can't be more than that. House is 3 bed plus a flat built from old garage but got convectors in there ( very small flat ) house is semi detached prob 5-6 rads in whole house, old range foam cylinder approx 150 ltr immersion element heated only from a timeswitch.

 

[Soulsurfer]

To be fair I have told him to look at upgrading consumer unit etc.. & sorting flat supply better etc.. as is a 6mm run from 3036 board using a cooker switch to isolate it before Cu in there ! Really old wiring too.

 

[Soulsurfer]

Is there an electric shower in the property? If so might have to think about a relay too.

Come to think of it I think there might be an Elec shower too.

 

[Soulsurfer]

On the efficiency side, looking at BG just now they have gas at 3.6p per kWh and elec at 12p. Electric more efficient? Not so much anymore with modern condensing boilers claiming 90% efficiency and internal voltage drop of say 3% there's only 7% difference. Adjusting for boiler efficiency that's 4p for gas. Forget the voltage drop and use the cheapest night rate of 6.5p for leccie and for the same heating I'm expecting him to pay 50% more at least. What have I missed ?

Electric here quoted as 10.22p per unit 20 hrs plus general tariff 14.5p per unit other 4 hrs
8 radiators in house £2,982.40 to install the boiler replacement.

 

[PEG]

Thanks Lee, and in reply to others who have also provided help & advice on this... yes I did say it would likely cost more to run but he said gas is costing £280 / month on DD and it can't be more than that. House is 3 bed plus a flat built from old garage but got convectors in there ( very small flat ) house is semi detached prob 5-6 rads in whole house, old range foam cylinder approx 150 ltr immersion element heated only from a timeswitch.

£280 a month,for gas only? He must have filled his cavity wall with liquid nitrogen,and have no roof