12 Radiators on a one pipe system!

[ISM]

A customer of mine has a ongoing issue with a rad which refuses to heat up. On two occaisions now I have balanced the system (which takes ages due to one pipe) to get the none working rad working, but after time it stops heating up. 2 Years ago BG did a boiler swap, but unsure if they flushed - to be hoenst Im not even sure if thats part of thier process.

Anyways, the pump is rather old, but wokring fine and reading 161 ohms across L & N. The selector is on 3 (110 watts). The system is open vented s plan, boiler in the garage, one pipe all in 15mm with 12 radiators (big house)!! some of which don't heat that well (furthest away) and 3 rads 1800mm long.

So my question is, how can I improve this system as nothing in the text book seems to be working!!??

The only thing ive not done is size the boiler against the rads and cylinder.

(

 

[Destroyer2813]

The problem is gonna be the whole sytem is 15mm feeding 12 rads, 15mm can only carry so much heat

 

[Roger Welton]

100% pipe sizing, also probably full of sludge.

 

[Destroyer2813]

Best advice to give em is to re-pipe as a two pipe system with full control to make the best use of there over priced BG boiler

 

[ISM]

Yes your quite right, but looking for something which is more practical or 'out of the box'.

 

[Roger Welton]

Sows ear and silk purse spring to mind.

 

[Mike Jackson]

try turning the pump speed down. One pipe systems rely on gravity convection to carry the heat up into the radiators, if the flow is too fast they won't heat very well.

Are there TRVs fitted to the system, standard TRVs can be too restrictive to allow proper gravity circulation on a one pipe system.

Powerflushing will not work on a one pipe system. All it will do is clean the main loop. A good chemical clean will help but if the rads are clagged up they need to come off and be flushed through.

 

[jtsplumbing]

What boiler did BG fit ? most modern boilers not suitable 1 pipe, how is water heated ?

 

[secret squirrel]

What boiler did BG fit ? most modern boilers not suitable 1 pipe, how is water heated ?

Can you explain why not?

I agree 15mm is not ideal size of pipe but I can't think why a boiler won't heat a 1 pipe system, clearly not as efficient, just interested in the reasons

 

[jtsplumbing]

Think it's to do with how fast boiler heats up. but 15mm pipe system, it's a wounder any of it gets hot, must be a pig to balance, do rads have swept tee's on F & R ?

 

[GQuigley67]

a 12 rad system all piped in 15mm ?? doesn't sound very good, the maximum rads i would do off of 15mm is 4 and that's small radiators. I'm suprised BG fitted a boiler on a one pipe system

 

[mfgs]

Think it's to do with how fast boiler heats up. but 15mm pipe system, it's a wounder any of it gets hot, must be a pig to balance, do rads have swept tee's on F & R ?

I have fitted a few Worcesters on 1 pipe systems and they work fine, just not as efficient.

When balancing you need to make sure no radiator is piped into the system as a loop, if that makes sense. Just in one side and out the other, not tee'd off the main pipe and into both valves. I have seen a few piped in this way and by balancing and turning down one end it can have a very bad effect on rads further along due to restricting the main flow through the system.

 

[Mickyplumb]

I have fitted a few Worcesters on 1 pipe systems and they work fine, just not as efficient.

When balancing you need to make sure no radiator is piped into the system as a loop, if that makes sense. Just in one side and out the other, not tee'd off the main pipe and into both valves. I have seen a few piped in this way and by balancing and turning down one end it can have a very bad effect on rads further along due to restricting the main flow through the system.

A friend of mine has a large house, single 15mm going all the way round. Flow and return ( if you can call it that on a single pipe sys ) of the rads just come off the same pipe. He had two rads that just wouldn't warm up to much more than 30 degrees. What we did was fit a couple of lock shields on each of the 2 rads and then simply put a couple of full bore valves between the flow and return of each rad. Water obviously always wants to take the path of least resistance but we altered that by throttling back these two valves to encourage water to go through the rads. Cured the symptoms but not the disease !!!!

 

[DaveTidy]

I agree with Micky Plumb regarding the valves to throttle it back as it's worked on my dad's system for 38 years with an Thorn M54 and they won't change it or the system all the time it works!! It's also 15mm on the whole circuit except for about 4 metres of 22mm coming off the boiler.

As for BG, they're meant to do a hot and cold flush as standard but a powerflush is a chargable extra. If they have followed the manufacturer's instructions then I don't know of one which states the boiler is suitable for a one pipe system!

The old Grundfos super selectric pumps used to give 193 ohms on speed 3 so if you're getting 161 ohms that isn't far off.

In my experience it always ends up being a re-pipe eventually but I guess that's for the customer to decide!!

 

[mfgs]

Worcester Bosch say its ok to install on a one pipe system, I called them to confirm this before fitting a boiler onto one.

 

[DaveTidy]

That's interesting for a manufacturer to say it's ok as I can't see how the temperature difference across the heat exchanger would be set-up correctly to the 11 or 20 degrees dependant upon the boiler. I'm sure if there was a heat exchanger scale or noise problem the first thing that would invalidate the guarantee would be would be that. Go figure, if they were confident you'd think it would be in the MI's.


I guess it's a little bit like you must have 20mb inlet pressure to the appliance but in practice if you haven't they may tell you their apliances need only 15mb (which I've had in the past)!!!!

 

[mfgs]

Their exact words were it will work fine, it just wont be as efficient due to the return temperature.