New rads on One Pipe System

busterjones

Just had 4 old single panel rads replaced with new double panel ones and had 2 new ones added.

2 of the replacements are heating to warm but not very hot. Fittings for both are at bottom, whereas I think old rads had feed in at top.

The other replacements are not heating at all.

Same with the new rads which have tees off existing 1 1/2 pipe with 3/4. The heat seems to travel passed the tee but cools quickly and doesn't get to the rads themselves.

Have bled all even opening valve, feed open in to system to maintain pressure and filling bucket for 10 mins to see if there were and air pockets. Heat slowly moved to the rads but still didn't heat. All rads have both fittings at bottom.

Any ideas of what else to try please?

It's a new boiler and pump Ideal 24kw.

Thanks 👍🏻

busterjones

Just to confirm, this is a one pipe system!

Lenar3556

Make sure all the lock shield valves are fully open. Also check the pump speed, it may be too high - try the lowest setting.

busterjones

Forgot to mention, I got TRV valves but from what I've read since, these aren't suited to one pipe system?

If possible could someone send me a link to a more suitable lockshield and valves please?

Thanks!

busterjones

Also, should valves be fitting at top for flow in and opposite bottom for out? Thanks!

Lenar3556

https://www.boards.ie/discussion/comment/122719398#Comment_122719398

They aren’t going to help, as they add additional resistance to the circuit when flow is already critical. I would suggest get rid of them as a first step. Myson Fullflow 3/4BSP would be a decent valve. Pegler would have something similar.

Lenar3556

https://www.boards.ie/discussion/comment/122719401#Comment_122719401

Yes, piping it with top (flow) and bottom entry points will improve heat transfer to the radiator. As will the use of swept tee’s on the flow and return connections to encourage flow through the radiator.

Have you any photos?

astrofool

Single pipe system would need careful balancing to work effectively, we ripped ours out and put in a feed/return system.

Our valves used to look something like this and worked ok with a TRV fitted:

Two pipe radiator valve for TKM system DN 15, G ¾ ET - Oventrop GmbH & Co. KG

Lenar3556

https://www.boards.ie/discussion/comment/122720216#Comment_122720216

You cannot really balance a single pipe system. It’s a very different principle to a two pipe.

You can get TRV’s to suit single pipe systems - nothing particularly fancy, just a larger bore. Danfoss high flow for example.

astrofool

https://www.boards.ie/discussion/comment/122720258#Comment_122720258

I know, when I say balance, I really mean making sure the rads downstream are sized appropriately to manage the lower temp water. The valve type I showed above worked well for us with the TRV, we never really had cold rads, but you ran into the case that the first rad on the pipe would get the room to temperature first and so on down the chain.

busterjones

https://www.boards.ie/discussion/comment/122719558#Comment_122719558

WhatsApp Image 2024-10-15 at 15.11.36_6ea47925 - Copy.jpg

WhatsApp Image 2024-10-15 at 15.11.36_9c022ed0.jpg

WhatsApp Image 2024-10-15 at 15.11.36_9f4f6238 - Copy.jpg

WhatsApp Image 2024-10-15 at 15.11.36_9f4f6238.jpg

WhatsApp Image 2024-10-15 at 15.11.36_87f9e328 - Copy.jpg

WhatsApp Image 2024-10-15 at 15.11.36_87f9e328.jpg

WhatsApp Image 2024-10-15 at 15.11.36_591c359e.jpg

WhatsApp Image 2024-10-15 at 15.11.36_db90cac2.jpg

WhatsApp Image 2024-10-15 at 15.11.36_e6c31441.jpg

Screenshot_20241015_155708_Samsung Internet.jpg

MOD cropped above image to remove Technicians name and details.

Pics added. Shows one of the replaced rads. Pipe runs behind at top and teed on both sides to bottom and has TRV and lock-shield - the pipe itself is very hot but no heat in the rad.

The vertical one has no heat at all. This is a replacement for old one and needed the space so trying a vertical - replaced the TRV etc with 1/2 inch elbows temporarily to see if TRV gave too much resistance, but no change.

Have also included pics of the plumbing under floorboards that's feeding the vertical rad. Its teed off what I think is 1 1/4 steel pipe. That pipe gets very hot but basically no heat moving through the tee.

Have included pic of the boiler too. Pump is built in and set at 70% as factory. Can only be adjusted to 100% as far as I can tell.

Lenar3556

One pipe systems aren’t very forgiving. Even when well designed there was just about enough flow though the radiator to heat it.

I don’t think radiators supplied in the form of drops from the primary circuit are going to work - the flow resistance through the radiator would be simply too high and it allows no possibility for convection currents to allow heat to rise from the primary circuit into the radiator.

Is the pipe to the vertical rad in 1/2”? Might be a bit small.

Pump speed is likely much too high. You would need some form of low loss header and repump from there.

All in all, I don’t think this is going to work. What are the prospects of converting this to a two pipe arrangement?

busterjones

https://www.boards.ie/discussion/comment/122722504#Comment_122722504

Difficult to convert to 2 pipe as some floors are concrete and would be very big job and more than we can afford right now!

Pipe to the vertical rad is 3/4 under the floorboards and then 1/2 at the rad itself.

Thanks for the advice!

John.G

Theoretically, this is the sort of "balancing" you need if you had the same output rads in the whole circuit.

busterjones

https://www.boards.ie/discussion/comment/122724252#Comment_122724252

Very impressive! Thank you!

whizbang

You need a control valve on the pipe between the 2 tee's for each of radiators. Is there such a thing as a 3port / diverter trv ?

Remove all the radiator valves, and check all piping to the rads should be same or bigger diameter as supply pipe.