Combi Boiler Immersion Heater

[hopebeck]

We are considering having an oil combi boiler installed. We currently have a direct immersion heater and cylinder tank which we would like to retain alongside a combi boiler, as back up / for use outside winter time.

In plumbing terms is it possible to have an immersion heater operating alongside a combi boiler - can the system be set up to allow this?

Thanks

 

[PlumbBobBob]

no i don't think you can have both. the idea of having a combi is to do away with tanks and cylinders. you could have a system boiler and an unvented cylinder.

 

[tamz]

You could but it would mean splitting up the plumbing system but it is impractical.
Either go for the combi and get rid of the cylinder or keep the cylinder and get a standard boiler fitted that will heat it and your radiators.

 

[Mbear]

no i don't think you can have both. the idea of having a combi is to do away with tanks and cylinders. you could have a system boiler and an unvented cylinder.

U can have both, it's very common in large old city flats round here. Combi feeds kitchen, heating Pipes are zoned to feed a unvented cyl which does the bathrooms for hw. It can be done, I've done it a couple of times

 

[E4gas]

U can have both, it's very common in large old city flats round here. Combi feeds kitchen, heating Pipes are zoned to feed a unvented cyl which does the bathrooms for hw. It can be done, I've done it a couple of times

Do you have the wiring plan for this system , I no a s plan is used, not 100 % sure

 

[E4gas]

U can have both, it's very common in large old city flats round here. Combi feeds kitchen, heating Pipes are zoned to feed a unvented cyl which does the bathrooms for hw. It can be done, I've done it a couple of times

Do you have the wiring plan for this system , I no a s plan is used, not 100 % sure

 

[tamz]

Just wired as an S plan using the grey and orange of the valves as volt free switch wires.

 

[tamz]

Nothing new in doing it. Here is a diagram from an old Vokera SP


If you want to do a Y plan the combi MUST have 230v switch wires eg a worcs

 

[Mbear]

Do you have the wiring plan for this system , I no a s plan is used, not 100 % sure

Use a normal s plan. The orange wires from 2portvalve feed the switched live in to the boiler instead of directly from a room stat

 

[Nat]

U can have both, it's very common in large old city flats round here. Combi feeds kitchen, heating Pipes are zoned to feed a unvented cyl which does the bathrooms for hw. It can be done, I've done it a couple of times

I've seen this and heard it can be considered the best kind of system but I don't understand why. Why not use a conventional boiler and use hot water from the cylinder for kitchen. Am I being fick?

 

[tamz]

It is a good set up on large houses where the boiler may be in the utility room or kitchen and the bathrooms are at the other end of the house.
Use the combi to supply the sink taps and the HW cylinder to supply the bathrooms.

It was quite popular in the 90's as it was a lot cheaper to buy a 28kw combi than it was to buy a 100,000btu std boiler so you got a combi and stuck it on a S plan.

 

[Nat]

It is a good set up on large houses where the boiler may be in the utility room or kitchen and the bathrooms are at the other end of the house.
Use the combi to supply the sink taps and the HW cylinder to supply the bathrooms.

It was quite popular in the 90's as it was a lot cheaper to buy a 28kw combi than it was to buy a 100,000btu std boiler so you got a combi and stuck it on a S plan.

I get it. So its really to help with long waits for hot water at the kitchen taps. Gotcha.

 

[Mbear]

I've seen this and heard it can be considered the best kind of system but I don't understand why. Why not use a conventional boiler and use hot water from the cylinder for kitchen. Am I being fick?

It means u can buy a combi for the same-ish price as a heat only boiler and have a reduced size and therefore cheaper and smaller cylinder

I'm considering it for my house when we re-do the bathroom. It'd mean I can run the bathroom and shower from a unvented cyl and leave the kitchen on the combi.

It just gives more options, I think it's a great way of doing it

 

[mkw9]

try

Mistral boilers - High efficiency condensing oil-fired boilers, Shropshire, UK

an oil combi boiler with a built in immersion heater

 

[PlumbBobBob]

U can have both, it's very common in large old city flats round here. Combi feeds kitchen, heating Pipes are zoned to feed a unvented cyl which does the bathrooms for hw. It can be done, I've done it a couple of times

i stand corrected

 

[Mbear]

i stand corrected

It's a Great setup for future ref mate. Especially in medium to large properties. The wiring is not hard. Simple S plan, it sounds harder than it is

 

[PlumbBobBob]

cheers i'll remember that

 

[tamz]

I wouldn't do it with an oil combi though as they have a large heat bank (usually around 30-40 litre) which gets priority heated. Waste of fuel for a sink tap.

 

[stevetheplumber]

I wouldn't do it with an oil combi though as they have a large heat bank (usually around 30-40 litre) which gets priority heated. Waste of fuel for a sink tap.

just ripped out the gas version wb heatslave ,what a nightmare job that was tight between to units couldnt remove worktop and the boiler was over a inch lower than the tiles so couldnt drain the heat store as stupid doc was vitually tiled in
lots of angle grinding and unscrewing to seperate the boiler from heat store then bar heatstore tank up and out
one thing i learnt is im never going to change a plate heat exchanger on one of these

 

[Daveelectrician]

So.. Do I have to supply the immersion element through a contractor, as the usually pull 13 amp? Or does the boiler supply the cylinder ?

 

[Nostrum]

No the immersion is wired independently as with an s plan arrangement. In essence the combi is just running an s plan as a conventional boiler would. the hot water the combi supplies directly, and the hot water stored in the cylinder, and also heated by the immersion if required (normally a back up) are completely separate.

 

[Daveelectrician]

No the immersion is wired independently as with an s plan arrangement. In essence the combi is just running an s plan as a conventional boiler would. the hot water the combi supplies directly, and the hot water stored in the cylinder, and also heated by the immersion if required (normally a back up) are completely separate.

Thank you, bailing out a fellow electrician tomorrow, as plumber done a runner. So far 2 electricians have looked at the system and failed.

 

[DirksPlumbing]

Thank you, bailing out a fellow electrician tomorrow, as plumber done a runner. So far 2 electricians have looked at the system and failed.

Please remember to make sure to have a 5A fuse in the spur for the oil boiler. That should have answered the question after the immerser anyway?

Setup is common as well if Solar thermal has been added. Usually one tap of the combi (minimum requirement). But oil is meantime a lot dearer per kW than a good electricity tariff and you have more losses on the oil too.

 

[lame plumber]

Please remember to make sure to have a 5A fuse in the spur for the oil boiler. That should have answered the question after the immerser anyway?

Setup is common as well if Solar thermal has been added. Usually one tap of the combi (minimum requirement). But oil is meantime a lot dearer per kW than a good electricity tariff and you have more losses on the oil too.

but elec doesnt have that nice oily smell:biggrin5: