Anyone with experience of replacing back boiler with combi?

[Deleted User]

Hi any advice or experience welcome.

I'm in the process of buying a Victorian terraced house which I have found out has a back boiler in the chimney breast behind a gas fire. Can anyone explain to me how this works especially the hot water? Theres a water tank in a cupboard, do I need the gas fire on to get hot water? How does that work in the summer? The bathroom had 2 cords one of which was the light and extractor fan so I'm assuming the other one is an immersion.

My plan is to get someone to remove it all and install a combi as that's all I know. I was also hoping to install a log burner in the hole it leaves behind but I've been reading I'll need a chimney flue liner so more expense. I love my quirky house but starting to feel a bit intimidated at all the work it needs. Thanks 

jefaz07

Your hot water and heating will generally be supplied by the back boiler.
It could be gravity, s plan or y plan system so can't really say from here  
A lot of the time the pipes going to the cylinder will be 1" if its a gravity system. Is there any valves in the cupboard with the hot water tank?
Could also check the programmer too, if you put the heating on and the hot water comes on with it is another sign.
You don't need to use the fire at all, the boiler behind it does the work. 
So many variables however so I hope that gives you an idea.

Reed_Richards

Some background information here: https://www.baxi.co.uk/faqs/what-is-a-back-boiler

tacpot12

By coincidence, I am organising the replacement of a back-boiler with a combi boiler for a friend. His system has a timer that can be set to turn either the hot water on, or the hot water on AND the central heating on (he can't have the CH on without having the hot water on). His system as the 1 inch pipes from the boiler downstairs to the cylinder upstairs. There is just one cold water tank in the property as the cylinder is a "Primatic" type which only needs the one tank vs. the more normal two. The central heating is operated by a pump next to the existing boiler. The timer turns the  central heating on by turning the boiler and pump on.

So check around for any sort of time switch. If the timer allows you to have the central heating on without having the   hot water on, you have S-plan or Y-plan system, but this doesn't really matter a great deal although if you have either of these systems it could make the replacement system a bit more efficient than my friend's will be.  

The replacement is fairly straightforward as he wants a Combi boiler and is happy to lose the cupboard and have the new boiler installed where the cupboard was. This means that the heating engineer can remove the cold water tank and the hot water tank, and use the 1 inch to take the central heating water from the new boiler down to where the central heating circuit starts on the ground floor. This will minimise the amount of disruption caused by having the back boiler replaced. 

[Deleted User]

Thank you both for your really helpful comments, it's a relief that I dont need the gas fire on to work the boiler. I'm trying to think of it as a combi hidden in the wall to get my head around it lol. 

Unfortunately all I know is there was one tank in the cupboard- the vendor had a bed pushed up practically against the door as its a small room so it was just a case of opening it a crack and going 'oh yes this is where the tank is'.

I would prefer the combi in the kitchen as I'd like to take the tank and cupboard out to free up the alcove and make more room - hopefully that wont be too difficult.

I think I might have to throw myself on my vendor's mercy and ask him to leave me instructions when I've exchanged!! 

FreeBear

Purplepenguin70 said: My plan is to get someone to remove it all and install a combi as that's all I know. I was also hoping to install a log burner in the hole it leaves behind but I've been reading I'll need a chimney flue liner so more expense. I love my quirky house but starting to feel a bit intimidated at all the work it needs. Thanks 

If you are planning on a wood stove, a couple of warnings. Installation costs are upwards of £1,000 plus the cost of the stove. Unless you are planning on infrequent use as a life-style statement, you get through quite a bit of wood. You will need a fair sized shed to store the logs in so that they remain dry - I have a 10x6 shed plus (currently) a similar sized pile seasoning under cover for winter 2022/3.

tacpot12

Providing there is space, you will be able to have the Combi in the kitchen, but there will be more disruption, mess and cost. 

TafParsons

Our Baxi gas fire/back boiler was removed from the living room and was replaced by a combi above the WC in the downstairs loo (easy access to power and water, a doddle to fit the flue and drain, and a short run to the gas meter). Only a small modification was needed to join to the radiator loops, and less than 3 feet of pipe to join to the hot water runs. The loo had no radiator (not enough space) but some waste heat from the combi keeps it cosy in winter. The entire rip out (including old pipes), fitting the boiler and also TRV valves around the house came in at under £1250. Our gas bills plummeted immediately.

[Deleted User]

Thank you that's really helpful