Combi Boiler Back Up Project

[Rog200455]

"I'd like a proper shower in the en-suite" said the wife.

"Ah", I said. "You will then lose the diversity of having an electric shower in the en-suite to use when the boiler breaks down and leaves the conventional shower in the main bathroom useless".

This fell on deaf ears.

To cut a long story short, as part of the en-suite refurbishment, I replaced the old electric shower in the en-suite with a conventional shower but also installed a 10kW instantaneous electric heater in the supply pipes to the en-suite.

I was lucky in that the H&C feeds to the en-suite run at garage ceiling level (the en-suite is above an integral garage) and it was simply a matter of mounting the water heater high-up on the garage wall. By means of a series of valves, it's possible to supply the hot pipe via the boiler or the electric heater. The old high current cable that previously ran to the electric shower was rerouted to the instantaneous heater.

This arrangement has the added benefit that, as well as the shower, the basin and bidet in the en-suite are also supplied from the electric heater in case of boiler breakdown.

I then got to thinking that every combi boiler installation could be backed-up this way. Simply install an instantaneous heater close to the boiler with a changeover system...

For what it's worth, I suppose I should add that I am an electrical engineer.

 

[roboughton]

A lot of homes have this sort of set up in that they have Immersion heaters. In my case my thermal store has two of them. When I get round to buying solar they will be run on that free sun as part of the install when I am not pulling the power for my own use.

Still a good idea though, maybe some pictures

 

[Rog200455]

I can see that having a copper cylinder for solar would be a must, however for most standard combi installations I think my solution is cheap and space saving. Here's a pic of heater in place

 

[roboughton]

I should say I have a pellet boiler so its again a bit different in the fact you have to have a tank. Love the idea of the electric backup, I may even put on in my garage when its done to give me hot water as there will be a toilet out in there.

 

[Rog200455]

Sorry for resurrecting this almost four year old thread but my boiler has broken and I'm using this project in anger - so glad I did it!

 

[Ian H]

Genius!! So you shut off the hot from the boiler and the heater feeds hot water direct from the cold pipe?

So if you did similar in, for example, an onsuite in a loft conversion you could supply it with a single cold pipe?

 

[ericmark]

I have also considered alternative domestic hot water, and yes glad you have highlighted this thread in a way, but really is should be a new thread with a link to this one.

As to an electric water heater there are 6 kW boilers which I am sure could be used as back up systems both for central heating and domestic hot water, but lose electric power and both fail, so I can boil water in a kettle, so DHW is not really a problem, it is home heating which is real problem, so I have an open fire and small stock of logs, never as yet used it, hope I will not need to, but that is more the type of back up I want, does not matter if I run out of oil or there is a power cut my back up still works.

 

[Rog200455]

Genius!! So you shut off the hot from the boiler and the heater feeds hot water direct from the cold pipe?

So if you did similar in, for example, an onsuite in a loft conversion you could supply it with a single cold pipe?

You certainly could. The other benefit I am finding is that the hot water comes through much sooner, as the source of heat is close to the place of use - I might leave the en-suite in this mode even when the new boiler is fitted...