Two boilers

[Jallybongo]

Hi all, I have two boilers fitted, one is an oil fired Rhino, the other is an electric Elterm 9 kw. I use the Rhino for central heating and hot water and plan to use the Elterm to boost the hot water when demand asks for it, we run a holiday home.

I have a 300L Tempest unvented cylinder and S plan control system

Is there a way to configure the system so that the Elterm kicks in when the water temperature gets too low.



Jally

 

[Madrab]

Would be an pretty complicated system TBH.

If it's a standard Tempest cylinder then you have only one coil, therefore the Rhino would run the primaries for that coil and would provide it with all the heat it can take. If you had another coil, say as in the solar tempest then you could potentially then run that 2nd coil from the Elterm as a top up and activate through a thermostat, like with a boost immersion. What is the water to be used for? There could also be the potential to fit a plate and use a thermostat to monitor the HW temp and switch up to the Elterm when the outlet temp drops but again it would be pretty complicated.

You may be better using say a high quality electric shower for part of the requirement. What version of Elterm is it?

 

[Gasguru]

The 9Kw Elterm will provide around 4 litres/min at shower temperature (ie about as good as a cheap electric shower) so if you think you're going to improve the hot water as it's being used it will make little difference.

All these electric boilers are a total waste of time...there are better/simpler options.

I'm not up to date with current oil prices but electric has always been significantly more expensive to provide heating/hot water.

Have you considered water flow limiters on the showers...a 300 litre cylinder should be more than enough.

Presumerably you've already got the 3Kw immersion heater wired up on the cyclinder to provide hot water backup if the oil boiler fails.

 

[Jallybongo]

Thanks for the replies. The water is used for showers and baths in a holiday home (18 guests) wiring to the bathrooms is nigh impossible as we have feature cornices in all the rooms. How would the thermostat on the outlet side of the HW pipework and would this be a pipe stat.

How about an extra indirect cylinder, how would the controls work with that.

I have the immersion wired in too.

Jally

 

[muggles]

As above, that electric boiler is going to be enormously expensive to run, and do very little to improve your hot water availability. Best place for it is eBay, which would then give you a bit of cash to put towards an improved oil-fired system. Two cylinders or a larger single cylinder with two high-recovery coils, and a pair of oil boilers, would be your best option I think.

 

[Lower]

You could put the electric heater on a timer so it only comes on at certain times and will only add heat if the oil fired boiler isn't keeping up with demand.