Electric combi boiler for underfloor heating and rads - off the grid

[serfer]

Hi all,

I'm new here and trying to get my head around the selection of boilers as none of them seem to have very detailed spec sheets. My property is off the mains gas grid, with no space for LPG or oil tanks. I can't afford biomass or air source pumps which leaves me with an electric boiler.

I would like the boiler to run the underfloor system, radiators and domestic hot water for a 3 bed, 2 bath home.
I would like it to be a combi boiler.

Anyone got any ideas of a good model?

Thanks!

 

[lame plumber]

move house it will cost you the earth to run or find room for an oil tank, they can be buried!

 

[serfer]

I have no space even to bury the tank.

Moving house use isnt really a helpful idea! I am looking for advice and assistance. I know electric combi may not be the cheapest option in terms of per unit of fuel, and I dont want to discuss running costs, refuelling, installation or servicing costs.

I am just wondering what electric combi boiler would be suited for ufh and rads and domestic hot water. 🙂

thx all

 

[SimonG]

You dont want a combi. You want an unvented direct cylinder heating up on cheap rate. Thats if you have the water pressure and flow. Then you need an amptec for your underfloor and an amptec for your rads. Then big pockets to pay the leccy bill.

 

[serfer]

No. Cheap rate isnt an option for me as I have huge amounts of electric running during the day / when the rate would be much higher than usual.

I save hundreds on installation and maintenance and I have very little space so combi electric is the way to go. This much i know and i dont need to hear alternatives thx v much for the input, but i really just would like thoughts on good electric combi boilers for rads, ufh and domestic hot water!

 

[SimonG]

Electric combi is not thecway to go, it wont do what you are after. Simple as, but what do we know, eh! Good luck.

 

[lame plumber]

customer always knows best................................

 

[Masood]

Simon is right, serfer. Electric combi will not give you anything like the flow rate of a gas boiler. To heat UFH and rads a smallish Amptec will do the trick. Direct unvented for hot water. It's irrelevant that you use loads of electricity during the day - the cheap rate you use during the night will still save you some money. If you're really not concerned about saving money then just run the immersions 24/7.

 

[gasmanrob]

Look at the electric heating company based in Scotland I've fitted a few of their units and they seem to be ok that said they have only ever been fitted in flats and one guy moved out 8 months later due to running costs.

To to get the heat load you need your going to need a 3 phase supply to run an average house electrics day to day plus allowance for maximum load in winter.

Personally for what your asking/adamant on doing I'd get 2/3 heatrae sadia inline boilers (tall slim pass through type) in tandem linked with an unvented hot water cylinder fed via a heavy duty water softener.

Id is also get solar panels on the roof. I know you've stated that the cost of renewables is out of your range, but you can get them free you won't earn a penny out of them like the people who own them but youll
be making a start on reducing an astronomical running cost.

And nod although you say there is no room for the alternatives, there is always a way always. How can you live of the beaten track cut off from mains gas and not have space? Equally if you are off mains gas I can't imagine you will have an overly adequate electrical supply

 

[chris watkins]

I save hundreds on installation and maintenance and I have very little space so combi electric is the way to go.
This much i know and i dont need to hear alternatives thx v much for the input, but i really just would like thoughts on good electric combi boilers for rads, ufh and domestic hot water!

If this much you know why are you bothering to ask on here?
The bit you clearly don't know is the basic laws of science & the limitation of the domestic house electrical supply.

We wouldn't even be recommend that you install a gas fired combi to supply the hot water to your two bathroom house at around 30kW it would provide a very poor hot water flow & not be able to provide the heating at the same time.
Lets just say you went with an electric version.
30kW = 30,000watts / 230Volts = 130 Amps, have you checked the size of your cut out fuse on the incoming electric supply to your house, if not go take a look.

 

[Nostrum]

Hang on. What have you got that's currently running the underfloor etc?

 

[Nostrum]

Are you a landlord?

 

[serfer]

Thanks everyone for the information! Its really helpful to get pro input. I own a little cottage, for me and family to live in, with no land, out in the country off the grid. There has never been a heating system in place - just a few old wood burners.

I have been been investigating heat source and distribution since November and have resigned myself to having no option other than electric. Or 47kg bottled calor gas. I really don't have much room downstairs (trying to start running a business from home that needs equipment and loads of storage) and the loft is 350yrs old and cant take the weight of a tank up there.

Re the electrics - I have just had the PME update for my earth and I'm running 60amps until my metre gets updated when I could go to 100A. The electric hardware, cabling, sockets and all will be done entirely from new next month.

I imagine the 75sqm ufh will be running a lot. 6 Upstairs rads used sparingly if at all. Really dreading the thought of high running costs. Why is combi no good? Is it because it would always be running?

 

[Gray0689]

It would work out cheaper to run cylinder gas than electric

 

[serfer]

In dorset the electric is 10p per unit. Cylinder gas is around 14.5p...

 

[Rickster123]

I'm lost. If you already have all the answers what was the question?

 

[serfer]

Electric is my only option but... I'm wondering why combi would be very expensive to run when compared to another electric system...

 

[chris watkins]

Why is combi no good? Is it because it would always be running?

Because it take large amounts of energy to heat water instantaneously (4.186J/degC/Litre).

That 30kW gas fired combi I was talking about will deliver something like 12Litres a minute @ a 35deg C rise in Temp just enough to supply one tap properly. If we took all of your current electrical supply & used it all to heat hot water it would be equivalent to a 13.8kW combi (60Amp x 230V=13,800w).
Get the idea ?
Ever used an electric shower ? they are limited to around 10.5Kw for a reason & you don't get a good shower out of them in the winter do you.

 

[serfer]

Heating water instantly?
I was hoping to find a combi with an internal store of 50-150 litres that is kept ticking over at a good temperature...

 

[lame plumber]

Heating water instantly?
I was hoping to find a combi with an internal store of 50-150 litres that is kept ticking over at a good temperature...

you dont seem to be listening to anyones advice at present!!