Balancing rads help.....

[Dee]

Hi

I have 2 rads that will not heat when other 27 rads are running.

I've turned all other rads off both flow and return and the 2 cold rads are now hot. What does this tell me?

What do I do now please? 

[SteamyTea]

To me it says that the two radiators that stop working have a higher pipework resistance to them, or from them.

Like electricity, water will take the path of least resistance.

So it is probably a case of balancing (maybe a greater flow rate will help), but if there are TVRs fitted, then that complicates it all.

[Dee]

I've got those 2 working by turning off all 17 other rads at both f and R and forcing the heat to them....worked! then going back through each rad, turning back on and tweaking the return side. 

I stopped last night with 4 furthest from the boiler to balance....this morning I can't get those 4 to heat up!!

They're all column rads with TRVs

 

[Dee]

So....if I go back along the chain of rads that preceed the 4 cold ones, do I tweak the lockshields more closed or  more open?

[JohnMo]

  On 21/12/2024 at 11:52, Dee said:

So....if I go back along the chain of rads that preceed the 4 cold ones, do I tweak the lockshields more closed or  more open?

Expand  

You are trying to make the system resistance similar everywhere. So if some parts are not getting enough flow, you have to increase resistance elsewhere, by closing the LS a little.

[Dee]

Thankyou for clarifying that!

Other issue is I'm not achieving anything close to 12⁰ across any of the rads try as I might....at the boiler the difference is only 9⁰

[JohnMo]

  On 22/12/2024 at 07:48, Dee said:

Other issue is I'm not achieving anything close to 12⁰ across any of the rads try as I might....at the boiler the difference is only 9⁰

Expand  

Are you room warm enough is your boiler running without too much cycling?

 

dT is all to do with flow rate, if you moving too much water through the system dT will be low. You could turn down your circulation pump. But if circulation pump speed is controlled by boiler then the boiler is happy with the dT so don't mess with it.

[marshian]

  On 22/12/2024 at 07:48, Dee said:

Thankyou for clarifying that!

Other issue is I'm not achieving anything close to 12⁰ across any of the rads try as I might....at the boiler the difference is only 9⁰

Expand  

Why is 12 deg important to you?

 

At 70 deg flow temp you might see that at the boiler but not if you are running flow temps the allow the boiler to be in condensing mode all the time

 

27 rads is a lot of rads do you have control of the pump or is it inside the boiler - if external I’d try a faster pump speed - it could be that there just isn’t enough pump pressure to overcome the circuit resistance at the extreme ends of the system

 

[marshian]

  On 22/12/2024 at 09:05, JohnMo said:

dT is all to do with flow rate, if you moving too much water through the system dT will be low. You could turn down your circulation pump. But if circulation pump speed is controlled by boiler then the boiler is happy with the dT so don't mess with it.

Expand  

dT is also related to flow temp - lower the flow temps the narrower the dT will be (for same circumstances)

[Dee]

That's always quoted as being the ideal temperature across f and R...I don't know enough to question that;)

 

At 70 deg flow temp....Boiler is set to 60⁰

 

27 rads TYPO! There are 19rads

Edited December 22, 2024 by Nickfromwales
Thread tidied

[JohnMo]

  On 22/12/2024 at 09:57, Dee said:

What is cycling??

Expand  

Every time the boiler starts and stops. Short cycle time affects gas consumption in a bad way. So an on/running time of about 6 mins or less isn't good.

 

  On 22/12/2024 at 09:57, Dee said:

it's set to 3.

If I turn it down will that effect the power to push the water to the end of the house

Expand  

Cannot answer that, you would have to try and see what happens.

[marshian]

@Dee please learn how to quote properly - write your responses under the quote of the post you are replying to - it’s horrible to untangle a mangled response where you’ve replied inside the quoted post

 

 

(Thread now tidied  )

Edited December 22, 2024 by Nickfromwales
Housekeeping

[marshian]

  On 22/12/2024 at 09:53, Dee said:

That's always quoted as being the ideal temperature across f and R...I don't know enough to question that;)

 

At 70 deg flow temp....Boiler is set to 60⁰

 

27 rads TYPO! There are 19rads

Expand  

I have rads which a best only have a drop between flow and return of 3 deg (towel rails are rubbish for this) and other T22 rads that are 8 to 9 deg  - only one rad in the house gets a drop of 10 deg and it a Triple panel, triple convector which is 1400 mm long by 700 mm high

 

12 deg is a legacy statement IMO from days of non condensing gas boilers - if you are using a condensing boiler you shouldn’t be running a  flow temp above 55 leaving the boiler - the boiler is then always in condensing mode and more efficient.

 

Now if your rads aren’t big enough at that flow temp then you have to go higher.

 

27 v 19 rads ok not as big as initially stated but still a large circuit

 

on the column rads do they all have built in diverters - if they don’t it’s normally obvious - the bottom is hot the rest of the rad luke warm

[Nickfromwales]

Thread tidied.   

 

@Dee

If you’ve got column rads then these are flow hungry, but will also bypass the flow potential of your pump (path of least resistance yaadaa-yaadaa), so basically try and draw a map of the rads and pipework in distance from pump > rad. 
Work these as an epicentre and adjust the LS valves according to % distance; eg 10 rads in a row in a straight line would have first LS set at 10% flow, 5th rad 50% flow 10th rad fully open.

 

Are all the rads fed from 15mm pipe work? 10mm to column rads is ‘no bueno’. Do you know how much 22/28mm (if any 28mm at all?) primary pipe work there is? And do you know if no more than 4 rads are fed off a run of 15mm pipework?

 

How old are the TRVs? These things don’t last forever. 

[marshian]

Screw the lock shields down to the point that the drop between flow and return on each rad is 12 deg at a flow temp of 60 and I reckon you will have a very unhappy boiler that short cycles a lot - so you will have a very high gas bill and a cold house.

 

Max number of cycles per hour should not exceed 6 but lower than that is preferred 

 

As an example - my house 13 rads currently has a boiler flow temp of 33.8 deg C and the boiler is running for 15 mins on and just circulating for 20 so 2 cycles per hour (but its all close to temp now)

 

 

[marshian]

  On 22/12/2024 at 13:48, Nickfromwales said:

Thread tidied.   

 

@Dee

If you’ve got column rads then these are flow hungry, but will also bypass the flow potential of your pump

 

How old are the TRVs? These things don’t last forever. 

Expand  

Thank you for tidying the thread

 

Agreed column rads need more flow but as they have a higher volume of water content they will work well at lower temps provided they have diverters (to stop short circuit) and you accept a slower warm up time

 

Trv’s don’t last for ever - yep cheap ones are rubbish but the other thing to consider is cheap lockshields can be very non linear and make a circuit hard to balance - either get ones with a decent valve authority or go the other way and fit TRV bodies with flow control function

[Nickfromwales]

FYI @Dee, the diverters are short / medium lengths of pipe or other to make the flow enter the rad vs just skip in and out like the SAS   

Same thing you’d get with the old twin-entry valves. 
 

 

 

[Dee]

  On 22/12/2024 at 13:34, marshian said:

@Dee please learn how to quote properly - write your responses under the quote of the post you are replying to - it’s horrible to untangle a mangled response where you’ve replied inside the quoted post

 

 

(Thread now tidied  )

Expand  

Sorry!

[Dee]

TRVs are pegler terrier. Some are 20yrs old but I'm replacing them one by one as too costly to do all at once.

Boiler cycles 3xhr

I'm getting abetter understanding now and thanks everyone for your input

[marshian]

  On 22/12/2024 at 15:54, Dee said:

TRVs are pegler terrier. Some are 20yrs old but I'm replacing them one by one as too costly to do all at once.

Expand  

 

Replacing them with what - same again??

 

Consider replacing them with a TRV body that either offers 6 adjustable flow settings (Drayton EB4 Bodies)

 

https://www.toolstation.com/drayton-wiser-smart-radiator-thermostat/p50334?store=null&utm_source=googleshopping&utm_medium=feed&utm_campaign=googleshoppingfeed&gad_source=1&gclid=CjwKCAiAjp-7BhBZEiwAmh9rBcR1wEcxM8xrixvxTn8Bc1p-xOOXyXr6japIK4NNc0FIGr8jR9ikXhoCQlEQAvD_BwE

 

Or the newer Flow control bodies

 

https://www.toolstation.com/drayton-auto-balancing-valve/p19480?store=null&utm_source=googleshopping&utm_medium=feed&utm_campaign=googleshoppingfeed&gad_source=1&gclid=CjwKCAiAjp-7BhBZEiwAmh9rBTeH1kZaQ_VTDZBUakAjHVXcBD_mDBrVqQzDCF5dQqvOZAbLI3VfHhoCTp8QAvD_BwE

 

Either of the above will enable you to run all the flow control at the TRV end and have the lockshield valve wide open

 

  On 22/12/2024 at 15:54, Dee said:

Boiler cycles 3xhr

I'm getting abetter understanding now and thanks everyone for your input

Expand  

 

OK so cycling isn't an issue

 

Ref Diverters - A lot of cheaper column rads don't have diverters or if they do the quality control isn't great - I had three column rads that all had different return temps despite very similar flow temps - One of them I was lucky to get any drop at all.

 

They basically work fine at higher flow temps when the heat rises up the columns faster than the flow thro the rad - but when flow temps are lower without effective diverters they don't work so well

 

https://www.bestheating.com/milano-flow-diverter-15mm-inlet-chrome-63476?gad_source=1&gclid=CjwKCAiAjp-7BhBZEiwAmh9rBQMqlsl_fWADI-zBoT93tixIGwN2tEfg3xTNkQsP8lPsOfTaOWPSDxoCAOIQAvD_BwE&gclsrc=aw.ds

 

These diverters fixed all of them to give a decent drop between flow and return and the rads get warm all over

 

If you've purchased good quality column rads with clearly marked flow and return ends and the location of the diverter and they are piped up with the flow and return correctly you should be fine

[Dee]

I didnt know such wonders existed in radiator valves! 

The rads are Acova, don't know where they stand on quality.  no idea if they have diverters as they're 20+ years old and I can't remember. 

Im definitely looking into swapping the valves over as an option.

If i were to replace two a month is there a way of doing this without draining down each time? ( I'll be doing the

work myself)

 

[Dee]

I've managed to get 2 of the 4 final cold rads to heat up...they're cast iron 4 column rads (that were here when we bought the place).

I had to crank down the 2 bathroom bathroom rails above the rads  to 'push' the heat through but it's worked.

The final 2 are having none of it so I'm giving up, closing them off completely, shutting the door and walking away!

[marshian]

  On 24/12/2024 at 08:28, Dee said:

I didnt know such wonders existed in radiator valves! 

 

<snip>

 

Im definitely looking into swapping the valves over as an option.

If i were to replace two a month is there a way of doing this without draining down each time? ( I'll be doing the

work myself)

 

Expand  

 

When I did the job I drained the system down in the summer (I had some other things I needed to do pipework wise) and I did all the EB4 Bodies at the same time (I had purchased them over the previous few months as and when I had a little spare in the household maintenance and repairs budget)

 

If I had my time again I would go for the Flow setting version as the 6 position ones on a few rads are either on a setting to low (but the next setting is far too much) or on a setting too high (but the setting below is far too low) In fact I may well replace all my EB4's with the flow setting ones next year just to "fix the few"

 

All my lock shields are wide open - The ability to control the flow thro a rad via the TRV body for me is so much better than trying to tweak lockshield valves that as soon as any TRV's in the system start to try to control room temps the circuit pressure changes and the lockshield valves are no longer set correctly

Edited December 24, 2024 by marshian

[marshian]

  On 24/12/2024 at 08:28, Dee said:

The rads are Acova, don't know where they stand on quality.  no idea if they have diverters as they're 20+ years old and I can't remember.

Expand  

 

Just for clarification when I hear the term column rads I think of this

 

 

But I have this suspicion based on a google that you mean

 

Edited December 24, 2024 by marshian

[Dee]

The second image are the style I have.

I'll look into those valves...thanks for a great peice of info and advice!