Balancing sealed system....Grrrr!

[Dee]

Hi, sorry if this stream is repeated but I'm very confused. 

 

I have a sealed system.

18 column rads.

I know all the valves work and there is no air in the system.

I've done temp check with a multimeter to get  baseline for each rad on flow and rtn and the numbers are all over the place!

2 ground floor rads are cold and don't heat up atall.        ( study and kitchen 2)

The rads before and after the study read,

Before LS 47.   TRV 59

After.   LS 33           60

Kitchen 2 the pipes drop down from Bed 4 above and that reads;

LS 58    TRV 50

 

I need clarity please;

Which pipe should be hottest TRV or LSV?

 

On 15 rads the TRV pipe is hottest. The other 3 the LS side is hotter.

 

The temp range varies from 5⁰c to 27⁰c....which is alot!

 

Does anyone see a pattern.

Thanks and Sorry!

 

 

[SimonD]

You'll probably hate this reply but I'm going to suggest you need to start again by collecting some basic information about your system and then taking it all methodically.

 

1.  what boiler do you have? Is it a system boiler/combi boiler with circulating pump built into it or is it a heat only pump with an external circulating pump in the airing cupboard or somewhere else?
2. Can you look up the installation servicing manual of the boiler as you might find recommended delta T for the boiler on commissioning - for example an Ideal Logic Max should be balanced for an 11 degree delta T whereas an Ideal Vogue Max should be 20C.
3. Fully open all your TRVs.
4. From cold switch on your heating and run around to find out which radiators get warm first and which ones last. The one that gets hot last is usually, but not always, the 'index' circuit, which is the circuit with the most pressure drop, or in other words, resistance.
5. While doing 4 above, check with your hand which pipe gets hot first on each radiator - this will determine the flow and return on each radiator. Your installer should really have installed them consistently with the same valves on each side but sometimes they get mixed up.
6. If you're using K type thermocouples on your multimeter, try and get some clip on ones or get some clip on thermometers - they need to be on the pipe for a while.
7. Then start to balance your radiators in the order that they warm up, so first rad to warm up first and then last rad last. You should find your lockshield will be more closed at the beginning to maybe fully open at the end of the circuit.
8. Lots of videos on Youtube to help but some aren't honest about how tricky it can be to get it balanced right sometimes!
9. Be patient.
10. Be careful wit the amount you turn each lockshield. Many of the cheaper ones can be fully closed to fully open in less than a full revolution so it can take time to get it right.
11. Don't be too perfectionist with each radiator - getting somewhere between 11-20C flow/return drop is pretty good.
12. You might need to look at the setting of the pump if you have any external pump.

HTH

Edited December 19, 2023 by SimonD

[MJNewton]

1 hour ago, Dee said:

Which pipe should be hottest TRV or LSV?

 

Flow should be the hottest, and Return coolest. How that correlates to the TRV and LSV depends on which way round they have been fitted. TRVs used to be directional - and hence would be located at the Flow end - but these days non chattering valve inserts are generally used thus making them bidirectional. Whether new or old you will have to work out which way round each of yours are by measuring the temperatures as you have been doing. Not that it matters too much for balancing - it will always be the LSV that you will be adjusting regardless which end of the radiator it has been put.

[Dee]

2 hours ago, SimonD said:

Be patient

My biggest flaw!!

However, I have balanced the system in the past from scratch and it worked perfectly but for unkonwn readons its decided not to. its a big house, and as the flow branches off in all directions I find it tricky to establish the order by which the rads heat up...is this critical?

 

Boiler is a very recent Baxi 400 with a heatrea sadia tank.

Photo attached of the multimeter I'm using.

 

Nearly all of the LSV are literally  barely cracked open atall and the rads are sooooo hot, is this normal??

 

Your process is invaluable and the first few steps I've never considered, so I will start there... (most Googles don't even mention those steps).

We had the system put in 18 yrs ago so I can't recall much about the spec. 

Thankyou so much! 

[JohnMo]

10 hours ago, Dee said:

Nearly all of the LSV are literally  barely cracked open atall and the rads are sooooo hot, is this normal??

Why don't you drop the flow temp, this will be more likely to be in the condensing range of the boiler (saving on gas usage) and will make it easier to adjust, as everything will heat up slower. 

[Dee]

1 hour ago, JohnMo said:

Why don't you drop the flow temp

Hi, how do I do that?

 

[MJNewton]

12 hours ago, Dee said:

Nearly all of the LSV are literally  barely cracked open atall and the rads are sooooo hot, is this normal??

 

Yes, entirely normal. After about 1/2-3/4 turns most LSVs are for all intents and propose fully open. Because of this only small adjustments should/can be made.

[JohnMo]

2 hours ago, Dee said:

Hi, how do I do that?

You drop the boiler flow temp on the boiler controller or at the boiler it's self.  There should be buttons to push or knob to turn at the boiler

[SimonD]

19 hours ago, Dee said:

My biggest flaw!!

However, I have balanced the system in the past from scratch and it worked perfectly but for unkonwn readons its decided not to. its a big house, and as the flow branches off in all directions I find it tricky to establish the order by which the rads heat up...is this critical?

 

On some systems it isn't critical but on others it is. I'm going to try and sort a system tomorrow that has almost exactly 20 flow return temp different at the boiler yet 3 radiators aren't getting any heat at all.

 

As water takes the path of least resistance, if you start at the beginning you're pushing the flow in the right direction from small pressure drop to greater pressure drop. Otherwise you can adjust the flow on a radiator somewhere along the circuit only to find that it's gone cold when you've adjusted the others - so the system remains unbalanced.

 

If you think about that balancing first means getting heat to all radiators on the circuit, this might help. Once they're all hot, try to get them roughly the same temperature and only then do you try to refine the temperature drop across the rad.

 

You may find that you do end up with a system where some rads might only drop by 10C and some by 20C, but then give you 20C drop across the boiler.

 

It's not an exact science, more of an art as hydronics can be a devil sometimes.

 

19 hours ago, Dee said:

Boiler is a very recent Baxi 400 with a heatrea sadia tank.

 

The Baxi 400 has a recommended difference of 20C

 

19 hours ago, Dee said:

Nearly all of the LSV are literally  barely cracked open atall and the rads are sooooo hot, is this normal??

 

Can be. Some lockshield can be so crap that it's almost impossible to regulate the flow. Sometimes barely a smidgen of a degree turn is all you need. Just depends on the brand of lockshield, with the main names being better to use - e.g. Danfoss and Drayton

 

19 hours ago, Dee said:

Photo attached of the multimeter I'm using.

 

The multi meter is fine, but I'd recommend you use something like the below. Using a thermocouple like the one you have makes it more of a pain than an already painful job needs to be:

 

 

https://www.ebay.co.uk/itm/115624510811?chn=ps&var=415642870400&norover=1&mkevt=1&mkrid=7101533165274578&mkcid=2&itemid=415642870400_115624510811&targetid=4585169654799844&device=c&mktype=&googleloc=&poi=&campaignid=412354547&mkgroupid=1305120599331881&rlsatarget=pla-4585169654799844&abcId=9300541&merchantid=87779

 

Good luck!

Edited December 20, 2023 by SimonD

[Dee]

Excellent advice! Thankyou so much.....weekend project, living the dream

[Dee]

This is driving me nuts!

I'm obsessing about the order the rads heat up as I figure if I get that wrong then balancing will never work...is this a correct assumption?

I've managed to fleetingly get some heat to one if the cold rads but only just....progress?

 

I recall when I balanced the system years ago that I took a temperature reading on the flow and return on the boiler? Why and do I need to do this again?

[SimonD]

31 minutes ago, Dee said:

This is driving me nuts!

I'm obsessing about the order the rads heat up as I figure if I get that wrong then balancing will never work...is this a correct assumption?

I've managed to fleetingly get some heat to one if the cold rads but only just....progress?

 

I recall when I balanced the system years ago that I took a temperature reading on the flow and return on the boiler? Why and do I need to do this again?

 

Yes, some progress.

 

Don't be too worried about it all, it's just the ideal way to do it. Starting when the system is cold, just calmly walk around the house feeling each radiator and the pipes feeding the rads. You'll soon get a sense of which ones get hotter sooner. If there's the odd rad you miss out, once the heating system is fully up to temp, then you can go round and feel/measure which ones are the hottest and start adjusting the LSV on those. You'll soon enough know if you've got it wrong and turned down the flow too much as the temp of the rad will go down too.

 

You need the flow/return boiler temps as that will tell you what difference there is at the boiler - like above you want 20C for your boiler. This will in part tell you if your rads are balanced as if there no difference, flow is just coming back to the boiler without being shared with the house, or whether you're losing too much heat. It can also tell you about the health of the system. Too much temperature difference can be a sign that there is a flow rate problem/too much pressure drop, too little difference can be down to too much flow. This can help you set the pump output correctly, or choose the correct proportional curve (if you have an external pump). It can also send you in the direction of checking the auto-bypass etc.

 

So yes, you need the boiler flow/return temps.

 

But a quick way to check if you can push hot water to the cold rads is to close the TRVs on the hottest radiators and then see what happens at the cold ones.

 

But again, be patient as it takes time for the system to respond, especially when you've close a LSV and you're waiting for the temp difference to change.

 

[Dee]

Thanks for the reassurance.

Over the summer the system was off completely for months, when turned on 6/18 were not heating atall so I did as you mentioned turned hot rads off and this did push the water to all the cold rads and they all heated perfectly ( also confirmed all valves were working). Over time by more luck than judgment 4 have now joined the hot team leaving two behind.

I've been stressing over the 12⁰ difference and now I understand this temp isn't appropriate for the baxi I have I can start again! 

Does it have to be 20⁰ exactly for every rad or within a range of 20⁰.

There's so much emphasis on 12⁰ on all the threads I have read?

I also have 3 vertical column rads is this a complication? (They're all column rads)

Thanks again 

[JohnMo]

 

On 19/12/2023 at 17:25, Dee said:

Does anyone see a pattern.

May be worth a read

 

 

 

https://www.heatgeek.com/balancing-heating-systems-the-ultimate-guide/

[SimonD]

51 minutes ago, Dee said:

I've been stressing over the 12⁰ difference and now I understand this temp isn't appropriate for the baxi I have I can start again! 

Does it have to be 20⁰ exactly for every rad or within a range of 20⁰.

There's so much emphasis on 12⁰ on all the threads I have read?

 

 

No you don't have to start again - temp difference at the rads doesn't necessarily translate to temp difference at the boiler.

 

Anything between about 11-20c on the rads is a great place to be. If you try for a perfect temp you're going to be pulling your hair out. As I mentioned above, the pump speed is important but not something you need to worry about if you have your pump internal to the boiler.

 

Also, if you don't get a perfect 20C at the boiler, don't fret. These systems are dynamic so there will always be some natural variation.

 

Main thing is to get heat to all your rads so they're all a fairly consistent temperature and then check the boiler flow & return.

 

Then report back 😊

 

[Dee]

3 hours ago, SimonD said:

3 hours ago, SimonD said:

Then report back 😊

I most certainly will! Thanks again 

 

[Dee]

Aha! I have 18 hot rads!!

My concern is though the temp diff varies massively from 1⁰ on rad #11 upto 23⁰ on rad# 9!

On 14 rads the TRV pipe is hotter than the LSV side and the LSV on rads furthest away from the boiler are open no more than 1/8th if that. In fact I would state that all the LSV are open open no more than 1/8th.

Does any of this matter?

 

Hope you all had a peaceful Xmas....Dee

[SimonD]

17 hours ago, Dee said:

Aha! I have 18 hot rads!!

My concern is though the temp diff varies massively from 1⁰ on rad #11 upto 23⁰ on rad# 9!

On 14 rads the TRV pipe is hotter than the LSV side and the LSV on rads furthest away from the boiler are open no more than 1/8th if that. In fact I would state that all the LSV are open open no more than 1/8th.

Does any of this matter?

 

Hope you all had a peaceful Xmas....Dee

 

Great progress! What are your flow and return temps at the boiler? These are going to be the most important because you want to make sure the boiler is in condensing mode for as much time as possible. It needs to be under 54C but just below 50 is better.

[Dee]

Are they the pipes with red and blue tape? Is that black thing the pump?

[SimonD]

3 hours ago, Dee said:

Are they the pipes with red and blue tape? Is that black thing the pump?

 

Yes, it'll be the pipes with red/blue tape. The black thing is what looks like a Magnaclean Atom system filter so not your pump. The pump is probably in your airing cupboard with the hot water cylinder.

[Dee]

5 hours ago, SimonD said:

It needs to be under 54C but just below 50 is better.

The hot pipe from the boiler is reading 56⁰.....how do I get it below 50⁰?

[SimonD]

1 hour ago, Dee said:

The hot pipe from the boiler is reading 56⁰.....how do I get it below 50⁰?

 

Measure the temperature of both pipes once the heating has been running for a while as we want to see both temps and the difference between them.

[Dee]

7 hours ago, SimonD said:

 

Cold pipe is 44⁰ hot pipe is 58⁰

[SimonD]

16 hours ago, Dee said:

Cold pipe is 44⁰ hot pipe is 58⁰

 

So you're not far off. As you've got some rads without much drop, I would be throttling back the flow a smidgen there. You'll only need to turn the LSV a small number of degrees, then wait and repeat as necessary. Then test flow/return temps again.

 

With respect to your pump, do you know what setting this is on?

[JohnMo]

17 hours ago, Dee said:

Cold pipe is 44⁰ hot pipe is 58⁰

To be in condensing mode it the return temp that is important not flow temp. You are well inside condensation mode.