Minimum distance between expansion tank and top radiator?

[Gazzie]

Hi,

Our house has a conventional central heating system. The boiler heats the water up and feeds the radiators and a hot water cylinder. There's an expansion tank in the loft.

Since we had our bathroom refitted 4-5 years ago, we've been experiencing issues with our towel radiator. We originally had a standard radiator on one wall, and replaced it with a 6 ft towel radiator. The radiator was also moved to another wall. The plumber use plastic pipes to reposition the radiator.

The radiator worked fine for about 4 months. Then started getting cold. After 12 months the central heating system was cleaned using sludge remover. The radiator worked fine for about 2 months. Then we had a power flush. The radiator worked fine for another 2 months. We then had a filter fitted to stop sludge building up in the pipework. The radiator worked fine for another 2 months.

It seems whenever the central heating system is drained down the radiator will work for a couple of months then stop working.

I've just spoken to a plumber who said it could be due to the expansion tank being too close to the top of the towel radiator. At a guess, I'd say there's about 2-3 foot distance between the two.

My guess is that when the plastic pipes warm up, they bend slightly. Over time this causes a kink in the pipe and restricts the flow of water. When the system is drained down, there's no weight in the plastic pipes, so they spring back into position and work for a short while.

Before I ask the plumber to start pulling up my beloved tiled floor, is it possible that the distance between the expansion tank and radiator is the cause of the issue?

Many Thanks!

 

[jtsplumbing]

you need about 3' from bottom of tank to highest point of system, it could be pumping over that's why you are getting lots of sludge, be a good idea to raise tank anyway.

 

[SafeGasInstall]

plumber can do many things there to sort out your problem , but I am not going to list them here ! If he is a heating man , not just a builder that fits bathrooms he WOULD know what he need to do to sort it out

 

[SimonG]

Got nothing to do with the pipes under the floor so can't understand why you'd want to be pulling up the floor.

 

[SafeGasInstall]

Hi,

Our house has a conventional central heating system. The boiler heats the water up and feeds the radiators and a hot water cylinder. There's an expansion tank in the loft.

Since we had our bathroom refitted 4-5 years ago, we've been experiencing issues with our towel radiator. We originally had a standard radiator on one wall, and replaced it with a 6 ft towel radiator. The radiator was also moved to another wall. The plumber use plastic pipes to reposition the radiator.

The radiator worked fine for about 4 months. Then started getting cold. After 12 months the central heating system was cleaned using sludge remover. The radiator worked fine for about 2 months. Then we had a power flush. The radiator worked fine for another 2 months. We then had a filter fitted to stop sludge building up in the pipework. The radiator worked fine for another 2 months.

It seems whenever the central heating system is drained down the radiator will work for a couple of months then stop working.

I've just spoken to a plumber who said it could be due to the expansion tank being too close to the top of the towel radiator. At a guess, I'd say there's about 2-3 foot distance between the two.

My guess is that when the plastic pipes warm up, they bend slightly. Over time this causes a kink in the pipe and restricts the flow of water. When the system is drained down, there's no weight in the plastic pipes, so they spring back into position and work for a short while.

Before I ask the plumber to start pulling up my beloved tiled floor, is it possible that the distance between the expansion tank and radiator is the cause of the issue?

Many Thanks!

plastic will not bend unless installed incorrectly

 

[lame plumber]

if pipes are springing around, then they need clippng down pronto!!!!!!!!!!!!!!!!!!!

 

[plumber0808]

Most manufactures state about a minimum of 300mm- 1ft static head from the highest point in the system to the water level which is easily achievable. It sounds like a pipework problem of some sorts.

Im assuming you have bled the radiator.

 

[Gazzie]

Thanks for all the replies.

Yes, we've bled the radiator. Just a progress report...

The plumber call round this morning. He had a quick look at the plastic pipes and said they're fine. The problematic radiator is upstairs in the bathroom. It's about 2m tall. As it's the tallest radiator in the house (and highest), the plumber is confident that the expansion tank is not high enough. In addition, there's 2m of water pushing against the hot water entering the radiator at the bottom.

Trouble is to raise the expansion tank, he'll also need to raise the water tank in the loft. It's not an easy job (especially working in the loft in this weather) and say it'll take a least 3 days effort.

The other options are to replace the radiator with a shorter one. He also suggested that a sealed system or combi boiler could fix the problem (as the system would have more pressure in it). As I'm skint at the moment, we'll probably go down the new radiator route.

 

[Dotty]

Sealing the system would probably work out cheaper.

And would definately work!