Added a new radiator but it's not that hot-headed any ideas?

[TT86]

Hello folks

A plumber added a radiator to one of our bedrooms that for some reason didn't have one. It's a three column retro style (but brand new) radiator.

He had the floors up and linked it to pipework supplying the bedroom next door- this radiator gets very warm.

The trouble with the new one is it's not hot enough! Yes it gets hot but the other upstairs ones (panel style) you can't really hold your hand on them for more than a few seconds. The new one is a fair bit cooler.

Any ideas what I can do?

A few rads around the house the TRV head is missing, not sure if this will affect it.

[fourfoldroot]

Did he balance the system ? That would be Plan A.

[TT86]

Sorry I should have said it's a normal horizontal style as below, assume this is the only way to mount these?

[TT86]

fourfoldroot said:

Did he balance the system ? That would be Plan A.

He certainly went about tweaking valves and shutting some down etc.

I guess I'll have to get him back to have another go! It's a freezing cold room with a large wooden door so I need volcanic heat ha

[Peanut Gallery]

If you turn down other TRVs in the system does this one get hot?

If so, open the lockshield on that rad a bit, half a turn or so.
Then go through the other rads that are hot and turn them down a quarter of a turn, wait for an hour / a day.
- Repeat until the new rad gets hot enough!

[B'stard Child]

TT86 said:

Sorry I should have said it's a normal horizontal style as below, assume this is the only way to mount these?

How big is the room?

Was the rad output sized to the heat loss of the room at the boiler target flow temp?

What is the declared heat output at T50?

My only comment is it looks a little small if it's in a large room or a room with high heat losses.

The output of column rads is never as good as panel rads with fins to convect the heat

[TT86]

Peanut Gallery said:

If you turn down other TRVs in the system does this one get hot?

If so, open the lockshield on that rad a bit, half a turn or so.
Then go through the other rads that are hot and turn them down a quarter of a turn, wait for an hour / a day.
- Repeat until the new rad gets hot enough!

Thanks for the helpful reply. Sadly about half of the TRVs are missing the heads- old house and old rads. The plumber tried the head from the new radiator on them but it didn't fit and he said it would likely be hard to find new heads for the old valves. I'll turn down the ones that have heads but equally I wasn't the others to still warm up nicely too- be interesting to see if it works in any case.

[TT86]

Love the username, thanks for the helpful reply.

The room is 4m by 3.3m. Almost 3 m talk mind. Corner of the house so two external walls plus the wooden double glazed door/window.

The BTU calculator seemed to suggest just over 5000. This radiator is 1000x600 and according the the specs hits 5000 at 50c. I probably could have gone slightly bigger but didn't want it impeding the doorway.

I always thought these column radiators got really hot. Id accept I had undersized if it was getting properly hot but currently it's just hitting a nicely warm feeling to the hand!

[B'stard Child]

TT86 said:

Love the username, thanks for the helpful reply.

Car related / historical nickname - no probs

TT86 said:

The room is 4m by 3.3m. Almost 3 m talk mind. Corner of the house so two external walls plus the wooden double glazed door/window.

The BTU calculator seemed to suggest just over 5000. This radiator is 1000x600 and according the the specs hits 5000 at 50c. I probably could have gone slightly bigger but didn't want it impeding the doorway.

OK at least some calculations went into the decision making process

TT86 said:

I always thought these column radiators got really hot. Id accept I had undersized if it was getting properly hot but currently it's just hitting a nicely warm feeling to the hand!

OK so it looks more likely to be an issue with flow rate thro this rad (either because it's being starved of flow by other rads or it's own lockshield is too restrictive)

Can you feel a decent drop between flow in pipe and flow out?

IR thermometers are useful things to have but in the event that you haven't got one or any other way of measuring rad flow and return you can get a good guide with touch

The only other comment I had is the end closest to the wall - if that has a TRV it might get affected by being in a corner like that and as a result shut down the flow earlier than is needed

[Philvrs]

TT86 said:

I always thought these column radiators got really hot. Id accept I had undersized if it was getting properly hot but currently it's just hitting a nicely warm feeling to the hand!

Is your thinking based on an old public building in the 80’s like a school or something? (Thats where I remember them from).
It would have had a boiler set to max because gas was almost free back then, unlike today with a 55c flow temp to maximise efficiency.
You try turning your boiler flow up to max for a day and see if it performs as you hoped.

[RotorRambler]

TT86 said:

Sorry I should have said it's a normal horizontal style as below, assume this is the only way to mount these?

Is the bottom the same shape as the top ? (cant quite see)
If it is, maybe its upside down?
The hot water will then shortcut across the ‘bottom’ . The actual bottom has a baffle inside to force it around.
Someone i know did that..

Edited by RotorRambler on Tuesday 20th January 20:05

[TT86]

B'stard Child said:

OK so it looks more likely to be an issue with flow rate thro this rad (either because it's being starved of flow by other rads or it's own lockshield is too restrictive)

Can you feel a decent drop between flow in pipe and flow out?

IR thermometers are useful things to have but in the event that you haven't got one or any other way of measuring rad flow and return you can get a good guide with touch

The only other comment I had is the end closest to the wall - if that has a TRV it might get affected by being in a corner like that and as a result shut down the flow earlier than is needed

Thanks mate, I've not had it on today as the wood burner won but I'll fire it up again tomorrow. You reminded me I have an IR thermometer in the shed I use for the pizza oven so that's a great shout.

The plumber did say our house was unusual as it has some many heated towel rails. Two in the kitchen (God knows why), one downstairs bathroom and three in the family bathroom and he suggested these would affect the flow.

Just odd that the other upstairs rads are toasty AF which does suggest your ideas are likely right.

I will check and report back.

[TT86]

RotorRambler said:

Is the bottom the same shape as the top ? (cant quite see)
If it is, maybe its upside down?
The hot water will then shortcut across the bottom . The actual bottom has a baffle inside to force it around.
Someone i know did that..


Deffo the right way up, the bottom holes were open and the bleed valve is at the top

Edited by RotorRambler on Tuesday 20th January 20:05

[TT86]

Philvrs said:

Is your thinking based on an old public building in the 80 s like a school or something? (Thats where I remember them from).
It would have had a boiler set to max because gas was almost free back then, unlike today with a 55c flow temp to maximise efficiency.
You try turning your boiler flow up to max for a day and see if it performs as you hoped.

Haha yes, they were volcanic weren't they! Lovely to sit against them in the school hall in the winter. Good shout with the boiler thanks, another suggestion I'll try this week.

[B'stard Child]

TT86 said:

B'stard Child said:

OK so it looks more likely to be an issue with flow rate thro this rad (either because it's being starved of flow by other rads or it's own lockshield is too restrictive)

Can you feel a decent drop between flow in pipe and flow out?

IR thermometers are useful things to have but in the event that you haven't got one or any other way of measuring rad flow and return you can get a good guide with touch

The only other comment I had is the end closest to the wall - if that has a TRV it might get affected by being in a corner like that and as a result shut down the flow earlier than is needed

Thanks mate, I've not had it on today as the wood burner won but I'll fire it up again tomorrow. You reminded me I have an IR thermometer in the shed I use for the pizza oven so that's a great shout.

Excellent (now the readings on white and shiney surfaces will be a couple of degrees off true temp but compare a few rads when the boiler is running - beside the inlet flow, middle top and beside the outlet return. This will give a fairly good picture of the flow rates thro the rads.

The delta between flow and return will depend on boiler flow temp and flow thro each rad if you are running higher flow temps then you'll see a bigger drop than if you are running lower flow temps

TT86 said:

The plumber did say our house was unusual as it has some many heated towel rails. Two in the kitchen (God knows why), one downstairs bathroom and three in the family bathroom and he suggested these would affect the flow.

towel rails are pretty poor heat emitters unless they are massive and are hard to get a decent drop between flow and return - they are just a poor design for a rad where the water just loves to take the shortest route (cos water is lazy)

We've got two and the best temp drop I can get across them is 3 deg but both in small rooms that don't need a lot of heat

If they are supplemental to other conventional rads then they need the smallest amount of flow possible to dry towels

TT86 said:

Just odd that the other upstairs rads are toasty AF which does suggest your ideas are likely right.

I will check and report back.

No worries

[119]

It’s certainly looks like a balancing issue and can be a royal pain in the ass to get right.

Speaking from experience!

In the end I shut down all of the lock shields on all the rads and start closest to the boiler opening those a quarter turn and around half to three quarters open on the rads further away.

[B'stard Child]

119 said:

It s certainly looks like a balancing issue and can be a royal pain in the ass to get right.

Speaking from experience!

Big circuit lots of rads yes

13 rads (two are towel rails) my go to guide has always been follow the wiki on here

https://www.pistonheads.com/gassing/topic.asp?h=0&...

119 said:

In the end I shut down all of the lock shields on all the rads and start closest to the boiler opening those a quarter turn and around half to three quarters open on the rads further away.

My circuit doesn't allow me to follow the hotest rad frst process as it splits into two (upstairs and downstairs) almost straight away after the pump.

I initially used Drayton EB4 TRV bodies as they have 6 selectable flow orifices which provided pretty good results but I had a few rooms that really needed finer control on flow rates so I've upgraded all of the TRV bodies to Danfos RAS-B2 PICV (Pressure independant control valves) they really are a game changer with a much finer control on flow rates that is unaffected by TRV intervention on other rads in the circuit

[GasEngineer]

It could possibly be the supply pipework if your plumber has just teed off the 15mm supply pipes to the radiator next door. Have you tried turning the next door radiator off to see if the new rad heats up any better?

[dave7108]

Haven't read all the replies but we have the same rads. I will say that you have to bleed them for ages. You think there is no air then you keep draining and all of a sudden a spurge of air comes out. It's worse on the tall columns.

[RotorRambler]

Does the bottom only get as hot as you’d expect?