Advice on replacing radiators

[RumUn]

Hi there

I wondered if anyone could give me some advice on replacing my radiators? I have lived in a Victorian terrace for three years now and during winter the heating struggles to get the house warmer than 18C when it is cold, even when the boiler is on permanently.

Basically I have realised that the radiators are too small to heat the house. Using a webpage I would estimate that the maximum output is around 6kW (If i have calculated correctly).

I've had couple of people round to quote for installing some bigger ones but one of the plumbers pointed out that my pipes all appear to 15 mm rather than 22mm. He suggested that I would need a whole new 22mm mains type system upstairs which could then drop down to heat downstairs because it is difficult to lift the floor because of tiles and laminate. The other plumber didn't mention this at all.

I was planning just to replace some of the downstairs rads and take up the output to around 10kW I think. But now I don't know whether this will work? I've read a few things which says that the pipes might get worn out etc. The boiler is an Ecotec Pro28. Any advice would be gratefully received. Thanks

 

[ianmcd]

I havent seen your layout but think you might be getting a bit confused with what you have been advised, you are very unlikely to need 22mm pipes to radiators in a domestic property, 15 mm is usually fine , think you mean the main runs but can only guess with the information provided. got afeeling that you have a problem elsewhere either undersized rads or poor insulation

 

[RumUn]

I havent seen your layout but think you might be getting a bit confused with what you have been advised, you are very unlikely to need 22mm pipes to radiators in a domestic property, 15 mm is usually fine , think you mean the main runs but can only guess with the information provided. got afeeling that you have a problem elsewhere either undersized rads or poor insulation

Sorry, what I mean is that the whole system is 15mm pipe. One plumber suggested that this was unusual and that some of it (the main circuit?) should be 22mm and this could cause problems if I put bigger rads on because the water would struggle to get around the whole system.

 

[ianmcd]

Sorry, what I mean is that the whole system is 15mm pipe. One plumber suggested that this was unusual and that some of it (the main circuit?) should be 22mm and this could cause problems if I put bigger rads on because the water would struggle to get around the whole system.

well he has seen the system I havent and it is very possible, the 15mm to each rad is fine but the main run might need 22mm without seeing it I wouldnt know, if that is his/hers advice I would go with it as they have seen the job we havent

 

[ReganAndCarter]

You probably have what is called background heating that was fitted in 60s or early 70s. Maybe from coal backburner that could only provide limited heat to rads. That's why only a few small rads were fitted and piped all in 15mm.

15mm can only carry a limited amount of heat. If you want to increase the size and number of rads you will need the main flow and return runs from boiler in 22mm, then teeing off to each rad in 15mm. If you stick with all 15mm and increase the rads, they won't heat properly and you will have wasted your time. The system would also be a nightmare to balance. Your second plumber seems to have overlooked all of this.

As a very rough estimate, your 10 Kw rads would be more than double what I would expect 15mm pipes to heat properly.

 

[JP_]

are the radiators all really hot? Because if they are not, then that might be a sign that just getting bigger rads might not help - if the boiler cannot heat the current ones up.

How is the insulation? Are the walls, floors and loft all properly insulated? If not, then it would be cheaper long-term to sort that out.

 

[ReganAndCarter]

The problem sounds like rads that can only emit 6Kw. 28Kw boiler is more than adequate for a terrace house.

 

[RumUn]

Regan and Carter - Thanks for the thoughts. From what you are saying I do need to invest in the new pipe system, althought that is more expensive and disruptive. I agree that the problem at the moment is that the overall output is just too low. I have smart thermostat so I can see graphs of how long it takes to heat up the rooms but I hoped that I could just replace the rads to fix it.

Jonbey - the rads do get hot at the moment and the insulation in the loft is pretty new. Solid walls though rather than cavity.

 

[JP_]

Well, I am in the process of insulating solid walls and suspended wooden floor. 50mm kingspan (or similar) glued onto the walls and put between floor joists makes a huge difference, and will also reduce (hopefully remove) all damp mould problems. Means renovating each room (we slept in the dining room for 3 months and now in what will be my son's room) but well worth the hassle if you plan to stay there for a while.

Gas will keep going up in price, insulation once fitted costs nothing.

This photo probably best shows what I've been up to.

Room now looks like this ... just waiting for the carpet, and electrician to come back

 

[RumUn]

Jonbey - thanks for the suggestion. I hadn't really thought of doing that. I have an offshot extension at the back which does suffer from damp on the first floor particularly, so that would definitely be an idea in there.

 

[JP_]

That reminds me of a room I had in Coventry one year (1994 I think) - box room above offshot extension on an old house. Freezing, damp and mouldy.

 

[youdontwanttodoitlikethat]

Well, I am in the process of insulating solid walls and suspended wooden floor. 50mm kingspan (or similar) glued onto the walls and put between floor joists makes a huge difference, and will also reduce (hopefully remove) all damp mould problems. Means renovating each room (we slept in the dining room for 3 months and now in what will be my son's room) but well worth the hassle if you plan to stay there for a while.

Gas will keep going up in price, insulation once fitted costs nothing.

This photo probably best shows what I've been up to.

View attachment 149458

Room now looks like this ... just waiting for the carpet, and electrician to come back

View attachment 149459

That looks interesting. I have some rooms with solid walls. Did you just attach insulation sheets to original wall? Then what, stick plasterboard straight to insulation or put some timber studs in? How did you do the floor? Do the floorboards just float on the insulation, or is there some timber support for boards?

Thanks for any advice.

 

[JP_]

Yeah, insulation stuck to wall with Everbuild pinkgrip foam (lots of). Then seals taped with insulation tape. Then plasterboard stuck over the top with pinkgrip.

For floor, just put battens 50mm down and layed 50mm kingspan over the top. All taped up again.