Radiator balancing

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Hi, I am having trouble with one particular radiator downstairs not getting as hot as the others, surprise surprise it's a new radiator in the new garage conversion (double panel radiator), I have checked the usual stuff and the trv is definitely not stuck and the locksheild is fully open, I have had several heating engineers round and they are all completely baffled as to why this new radiator is not heating up as quickly as the others.
My system now has 10 radiators 5 upstairs 5 downstairs no microbore just the main 22mm flow and return leaving the airing cupboard and each radiator teed off in 15mm, I have asked the engineers if this a balancing issue and if this kind of thing is pretty common and I got varying replies, one engineer said "on a system like yours you should be able to have all locksheilds wide open and no need to balance as the trvs control the flow to each radiator, he suggested just to turn the pump to max (3) its currently on mid (2).
The other engineer said almost the opposite he said you only want the locksheilds on each rad open about a 1/4 to 1/2 turn as most locksheilds become useless at restricting flow once you exceed half a turn, he also says if water flows through the radiators too fast they won't heat properly does this sound correct?
Final engineer said we just set them all half open "count the number of turns on the locksheilds and half it"
Who is correct here? I am about to have an experiment with the system and see what works but currently all the original radiators heat fine and it's only the new radiator that is struggling to heat fully but the flow pipe to it is red hot the same as the flow pipes to all the other rads.
Hope this makes sense any help advice would be appreciated
Thanks
 
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Have you turned off all the others leaving only the non working one open? If so, does it heat up?
 
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I have found DIY setting of the lock shield is not easy, the plumber uses a differential thermometer connected to inlet and outlet of each radiator and sets the temperature drop to around 15ºC, I tried with a aim and read thermometer and the readings were not steady enough to use.

I starting at nearest to boiler in mothers old house, turning off the lock shield waiting for pipes to cool, then turning on ¼ turn at a time until a little warmth felt, leaving some time between each ¼ turn so chance for water to heat pipe, and slowly moved further and further away from the boiler.

However it was not perfect, although better, so then I used the report from the TRV heads, 4 TRVs-1.jpg 4 of my heads show both target and current, and I moved one of these heads radiator to radiator to set lock shield valve, then once set refitted heads which only show target, and if current over target close a little, if reverse on repeated inspection open a little, and I can say once set the rooms were spot on, set to 20ºC they went to 20ºC although last 2ºC was slow, so tended to set 7 am to 22ºC then at 8 am to 20ºC as the anti-hysteresis software was OTT.

With mothers modulating gas boiler this worked spot on, the hall TRV set slightly lower than hall wall thermostat, so normally in Winter boiler would only turn off on a change of house temperature for example at bed time, in summer hall over the 18ºC wall thermostat set at so boiler did not run in summer.

I was very impressed how once set each room was at temperature set, however tried to repeat with this house, this time boiler not a gas modulating boiler but an oil boiler that simply turns on/off. The setting did not work anywhere near as well, the main problem is where to fit the wall thermostat, it clearly needs to be in an entrance level room, but every entrance level room has an outside door, we have 4 outside doors, also want in a room normally kept cool, so it switches off in the summer, but the hall is in the middle of the house, it is not the heating, but the cooling which presents the problem, the hall cools slower than other rooms, answer is multi wall thermostats or a thermostat linked to the TRV heads, I thought my Nest Gen 3 would link to TRV heads, seems I got this wrong.

one particular radiator downstairs not getting as hot as the others
This is not a fault in its self, if the radiator is larger than required it will be cooler, the living room at mothers house the radiator was barely warm most of the time, but the room was at the temperature set for the room, in a modern house the TRV is king, unless linked to the TRV the wall thermostat is only there to stop boiler cycling as summer approaches.

With linked wall thermostats then it is more of a hub than a wall thermostat.
 
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Hi, yes with all the other rads off it heats up fully no problem.

Sounds like it is definitely a balancing issue then, https://www.diynot.com/wiki/Plumbing:faq2.

Initially you could turn all radiators off and just crack open the lockshield valves a bit (it doesn't take much for water to flow) while leaving the problem one fully open. See what happens
 
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Who is correct here?

None of them. If the system needs balanced, because you are having a problem with one particular radiator, then you wouldn't have all lockshields set the same, which they all seem to be suggesting.
 
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I seem to remember there is a TRV which doubles as a lock shield valve, never used one myself, but know they exist, the lock shield valve controls the flow in the radiators, a TRV takes time to close, so if flow is too high, the radiator gets stinking hot before the valve has chance to close, causing a hysteresis with the room temperature where it see-saws hot to cool.

Remember the wall thermostat in most cases is only there to stop boiler cycling when summer comes, it is not to control room temperature, the TRV does that.

There are exceptions to every rule, and with a e-bus linked wall thermostat it may control one room, but in the main they just stop boiler cycling. Where the thermostat controls one room, that rooms needs to be the last to get warm, so the control room does not want to be living room as don't want living room as last room to get warm.
 
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None of them. If the system needs balanced, because you are having a problem with one particular radiator, then you wouldn't have all lockshields set the same, which they all seem to be suggesting.
Thanks, I will do as you suggest, few things I appreciate it's a how long is a piece of string question but on my system there are 10 radiators 5 upstairs 5 downstairs, as a rough guide how would each locksheild be set for my system? So say the closest rad is 1/4 turn and the problem radiator which is the furthest away is fully open, how would the locksheilds for the radiators inbetween be set?
Also is it normal for towel rails (not electric) to heat a bit slower than normal radiators? Also probably stupid question but there is one radiator with just a wheel head and obviously locksheild, should I set the wheel head half way or fully open or will it not matter? I take it the flow through the radiator is completely governed by the locksheild position rather than the trv or wheelhead?
Thanks just trying to make sense of my system
 
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as a rough guide how would each locksheild set for my system?

Crank them all open 1/4 turn (or less) and open the problematic one fully. See what happens. If any are not heating fully then open the lockshield a touch more.

Also is it normal for towel rails (not electric) to heat a bit slower than normal radiators?

Not really, but you may just be sensing them differently as radiators are flat panels where as towel rails are just tubes (normally). Hard to tell by touch alone.

should I set the wheel head half way or fully open or will it not matter? I take it the flow through the radiator is completely governed by the locksheild position rather than the trv or wheelhead?

Same as the others, just crank it open slightly. Lockshields and wheelheads are the same valves with different heads. It doesn't really matter which one you close but the lockshield is harder to tamper with in the future once set.
 
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Crank them all open 1/4 turn (or less) and open the problematic one fully. See what happens. If any are not heating fully then open the lockshield a touch more.



Not really, but you may just be sensing them differently as radiators are flat panels where as towel rails are just tubes (normally). Hard to tell by touch alone.



Same as the others, just crank it open slightly. Lockshields and wheelheads are the same valves with different heads. It doesn't really matter which one you close but the lockshield is harder to tamper with in the future once set.
Thanks will give that a go
 
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Hi just an update, as it's a day off I have set the system the way denso13 suggested and that has fixed the problem the problematic radiator now heats up fully the only rad that struggled a bit on 1/4 turn was the lounge rad (biggest rad) which is 1600x450 double panel I increased this to 1/2 a turn and that did the trick, the rest were fine and didn't need any adjustments so I'm more than happy, It was just a 30 minute test I did with all trvs set to max and they were all fully heated within the half hour boost.
Upstairs radiators were originally set to 3/4 off a turn and downstairs radiator (except the new radiator) were set to a full turn and 1/4 pretty much half open, they were obviously set far too high?

Just one more thing in the airing cupboard there are two gatevalves one is 22mm which is the return from the coil and the other is a 15mm bypass, I have carefully counted the number of turns and the 22mm gatevalve has been set to one full turn and 1/4, the 15mm bypass valve was only open at a 1/4 turn, would you say these valves are correctly set? System is a y plan gravity pumped with f and e and the boiler is a Worcester 18ri if that helps?
Thanks
 
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Makes you wonder at the skill level of the engineers you spoke to originally, this was clearly a balancing issue so why were they puzzled!
 
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If all seems to be working ok then I wouldn't adjust them.
Hi again, I have tested the hot water and heating combined with all trvs set to max, I have not altered any locksheilds because as I've said it's all working perfectly at least in heating only but surprise surprise when hot water is running the problematic radiator including the big radiator in the living room just don't want to heat up at least not very well they are hottish at the top and cold at the bottom and their return pipes are barely warm again this was just a half hour test after running the bath to trigger the hot water, the rest of the radiators were fine and heated up fully within the half hour.

Is it safe to turn this balancing valve down to a 1/4 turn? its currently set at one full turn and 1/4 from closed, (it takes 4 full turn and 1/4 from fully open to fully closed) my fear is i don't want to burn out the pump by setting this valve too low, so what is the safest amount I can lower this valve? The bypass is set to a 1/4 turn so there is not much I can do with this.

Do I need to do anything? Is it fairly normal for everything not to heat up fully when both heating and hot water are running? Bearing in mind this is worst case with all trvs set to max which I believe is fully open and bypasses thermostat?, ordinarily I would have upstairs set to 2 and downstairs set to 3.
Should I turn up the pump it's currently on mid (2)?
Or is it best to just keep the hot water and heating separate but in doing so wouldn't that defeat the whole point of this balancing valve in the first place?
Hope this makes sense
Thanks
 
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