Balancing a Zoned System

[redapple]

Hi

I was wondering If I might be able to get some help in balancing my central heating system.
I recently switched on the heating and found some radiators are hotter than others. It is a new system and was flushed.
My plumber told me that I would need to balance it and gave me a general idea but to be honest after doing some reading I thought better ask.

I have a Worchester Bosch FS 30 CDI. I currently have it set to setting 4 65C. It is located on the Third Floor

3 floored house with a bottom floor extension
- first floor 7 radiators
- second floor 5 radiators
- third floor 2 radiators

Unvented cylinder tank fitted with AVB located on second floor.

The system is split up into 4 Zones

I have a digital thermometer 🙂

I have included a diagram hope it doesn't make it too confusing.

I am not too sure if I turn all the zones on and then measure which order they heat up or do each zone separately?

When adjusting the lock shield from being fully open to closing what temperatures on flow and return I should be looking for allow the boiler to operate efficiently? and should I turn the boiler to max temperature or keep it at setting 4 when balancing?

Thanks any help much appreciated 🙂

 

[chris watkins]

Three questions if you will, before we start, please.
1. Who designed the system is it new or old pipework / rad's?
2. I take it there are some zone valves some where ?
3. Are the return pipework connections back to the boiler installed as shown in your drawing ?

 

[SimonG]

Three questions if you will, before we start, please.
1. Who designed the system is it new or old pipework / rad's?
2. I take it there are some zone valves some where ?
3. Are the return pipework connections back to the boiler installed as shown in your drawing ?

I know what you're thinking Chris 🙂

 

[AWheating]

and is there gate valve on the cylinder return?

id be supprised if the system was common'd together like the drawing but you never know.

 

[Dannypipe]

I'm off out, but I'll read this one with interest later!

 

[redapple]

thanks for getting back so quickly

The rads is old pipe work but the boiler piping up to pump is new pipe 28mm it was done by a corgi register plumber

It has 4 motorised valves 🙂 sorry should have put them in they are right after the pump.

I think the diagram has created more confusion than I intended really, it was a just a general layout of the flow and return pipe work ,didn't include vent and feed and other stuff. Just so you could see the placement of the boiler and rads

 

[chris watkins]

Sorry but one last question, who spec'ed the pump & Auto Bypass ? & day you know what the pump is set to ?
Any reason why the plumber did not balance the system after completing the work & left it for you?
I am just trying to find the alpha commissioning guide.

 

[redapple]

No problems thanks for replying

The pump is set to autoadapt, the plumber spec'ed the pump and auto bypass.
I had a lot of trouble with the electronics to be honest, the guy panicked when he saw the wiring junction box as it was like a plate of spaghetti and he completed everything else but the wiring.

If I am totally honest I have been less then impressed with the plumbers I have called out in London Area. They charge a bomb and then seem do the quickest job possible, Everyone I speak about plumbers here says the same thing. It has taught me a lessen to pay when the job is done and to get a contract for the work details.

Thanks to Mike on here I wired it up with his help and it is working no problems. The original plumber did tell me the system would need balancing once everything is up and running, and did tell how to balance it by just adjusting the lock-shield on each rad, but after reading how to actually balance a system I thought I better come on here and get the advice how to do it properly especially for a zoned system.

 

[chris watkins]

Sorry for the delay redapple, I could not find info had to find on-line, please see link

http://www.newtonnet.co.uk/permanent/GrundfosDocs/BypassCommissioningAlpha2or2L.pdf

As you will see you should not need a by-pass auto or manual if the pump is used in auto mode.

If you think about how the pump works it will become clear that it will not be able to open the the by-pass valve spring & if it did the pump would go to full speed again, which is not what we want.

I will leave this with you for the moment to have a look through & come back to me with the following - are the rad's fitted with TRV's ? If so, do you have them fitted to all the rads ?

 

[redapple]

Thank you Sir all help much appreciated 🙂

Yes all rads upgraded with TRV's and new Lockshields, with one rad having a double lockshield on the ground floor

Sorry the orginal pump was a 15/50 selectric and then this was upgraded to alpha 2 15/60 as 15/50 was not powerful enough the the pipe distances and 14 rads and new tank or so I was told

 

[Mike Jackson]

I'd set the pump to manual speed 3 initially and see if you can get heat everywhere to start with. Once you get everything hot you can look at reducing the pump speed whilst still keeping everything hot.


Sent from my iPad using Tapatalk HD

 

[redapple]

Hi Mike

Thanks sorry should have mentioned that when I set the Boiler to Max and set to pump 3 with all lockshields open all the radiators heat up. What I wasn't sure of is how I should go about reducing:

1. Do still keep boiler to max or set it to 65C when adjusting the lockshields?
2. When counting which radiators heat up first do I do zone by zone or just open all the valves for each floor and count which ones heat first?
3. And I have a digi thermometer reader , what temperature should I be looking for on the flow and return
for each rad?

And if you can think if anything else I might have missed out🙂

 

[Nostrum]

Hi,

I would open all motorised valves onto manually open and treat the system as 1 zone for balancing. The trv heads should either be removed or on maximum. Set pump on a constant speed as said and aim for a 20 degree differential across the rads. The boiler thermostat will depend on the design temperature of the system, size of rad's etc. It shouldn't make much of a difference for balancing, but you may find you can increase/decrease it once the system is up an running.

The autoadapt pump should take of the zones shutting down etc so you need to make sure your delivering the correct quantity of heat to each radiator on a worst case scenario.

 

[Dannypipe]

I'm with Sam. Exactly what I would do.

 

[chris watkins]

& me too, thanks Sam save me from typing.
Only thing to add may be is to close the Auto-bypass down as far as poss (turn knob clockwise as far as possible) & you may what to have the HW zone valve closed if you intended not to have the hot water on with the heating (I would recommend this) time the HW to come on before the heating.

 

[redapple]

Sorry one question

When you say aim for a "20 degree differential across the rads". Does this mean to measure the flow pipe temperature into the rad and then return pipe from it should be -20 degrees of that temperature?

Thank you for the advice.

​

 

[Subby]

Sorry one question

When you say aim for a "20 degree differential across the rads". Does this mean to measure the flow pipe temperature into the rad and then return pipe from it should be -20 degrees of that temperature?

Thank you for the advice.

​

That is correct

 

[chris watkins]

Yes,
You may what to start off by opening up the furrest rads away from the boiler / or point where all the zone valves are & almost close the ones which are closest (& something in between for the others). Then use the temp diff to fine turn, until all the rad's heat up at the same time & are all at about the same temp.

 

[redapple]

thank you for the help 🙂

I will spend next weekend fine tuning and will get back with the results