Single pipe central heating

[Graham22]

My son has moved house (with his young family) and the central heating is very poor. He had a heating engineer round who was completely stumped but then realised it is what he calls a single pipe system.
He has explained that the hot water goes from radiator to radiator in turn, so when it reaches the last rad (where the baby sleeps), it really is not warm at all.
He also explained that they cannot use any thermostatic valves (even tho fitted) as that will stop the entire system.

Does that make sense and is there anything he can do to improve the temperature in the baby's room, without replacing the whole system (eg would a stronger water pump help?)

Many thanks
Graham

 

[D_Hailsham]

He has explained that the hot water goes from radiator to radiator in turn, so when it reaches the last rad (where the baby sleeps), it really is not warm at all.

On a properly designed one pipe system there is a pipe which bypasses each rad, so only a portion of the flow (approx 30%) actually goes through the rad. The water flowing through the rad then mixes with the water through the bypass and enters the next rad at a slightly lower temperature. This is compensated for by installing increasingly 'oversized' rads. (The output of a rad depends on water temperature). The total temperature drop over the system will normally be about 11C.

This pic shows the difference between a one-pipe and two-pipe system.

View media item 17739

He also explained that they cannot use any thermostatic valves (even tho fitted) as that will stop the entire system.

Provided each rad is properly bypassed, you can use TRVs; but they have to be specifically designed for a single pipe system.

 

[Graham22]

Thanks, that is helpful. Sadly I am almost certain my son doesnt have any bypass pipework to the rads. The first is very hot and the last is barely warm. The temperature drop is huge.
Is it possible to fit a stronger pump to speed the water rounds faster, or any other low cost ideas?

Thanks

Graham

 

[RF Lighting]

I'm no plumber, but balancing the system might help things a bit.

 

[Graham22]

Not sure how do I do that?
All valves are completely open. If I reduce the flow into any rad, surely that will just make the entire system less effective?
Thats why I was wondering if I could speed up flow with stronger pump, or something
Graham

 

[doitall]

Not sure how do I do that?
All valves are completely open. If I reduce the flow into any rad, surely that will just make the entire system less effective?
Thats why I was wondering if I could speed up flow with stronger pump, or something
Graham

Hi,

Can you post a pic or two of the pipework to the rads.

So far your plumber who clearly hasn't a clue what he/she is talking about, is trying to baffle you with bull.

No a bigger pump will not make it better.

Yes you can have TRV's but they must be suitable for a one pipe system type, and is likely the problem, and the reason for the pic.

A good one pipe system, and you wouldn't know the difference to a two pipe system.

Pss the valves should be fully open.

 

[Graham22]

Hi
I cant do any pics, as it is at my sons home, but the pipes come out of floor together at centre point under each rad, one then going to left rad valve, and the other to the right.
The plumber seems a really genuine guy - it was my idea about maybe trying to push water faster, not his.

 

[kevplumb]

I'm no plumber, but balancing the system might help things a bit.

yer right
yer cant balance a one pipe systep with no bypasses
stick to twistin copper go plat with swa

 

[doitall]

Hi
I cant do any pics, as it is at my sons home, but the pipes come out of floor together at centre point under each rad, one then going to left rad valve, and the other to the right.
The plumber seems a really genuine guy - it was my idea about maybe trying to push water faster, not his.

Don't sound like a one pipe to me.

With a one pipe the tees to the rad needs to be as far apart as posible.

 

[Agile]

Easy to see if its a one pipe!

Just turn of ONE rad valve and everything on an ( unbypassed ) one pipe will go cold!

You can increase the flow rate by increasing the pump pressure. Usually by adding a second similar pump in series. But thats likely to make it noisy.

Your problem may well be that standard TRVs have been added and they are restricting the flow!

Tony

 

[doitall]

Easy to see if its a one pipe!

Just turn of ONE rad valve and everything on an ( unbypassed ) one pipe will go cold!

You can increase the flow rate by increasing the pump pressure. Usually by adding a second similar pump in series. But thats likely to make it noisy.

Your problem may well be that standard TRVs have been added and they are restricting the flow!

Tony

Not very well thought out that Tony.

Did you know if you turn one valve off on any radiator it will go cold.

 

[Agile]

I said that "everything on a one pipe" would go cold meaning "all the rads" !

30 min later even the house will go cold too!

 

[doitall]

What it needs is someone to look under the floor.

If it really is a one pipe and the tees are close together then it wont work.

On the other hand if it's a feed in feed out bodge, then as soon as the first TRV closes the lot goes as you said and the boiler dances on the wall.

 

[Agile]

Boiler dancing on the wall?

It might be one of the Ecotecs which cannot dance!

 

[kevplumb]

pitcher tees john