Grundfos Alpha 3 Pump Settings for Hydronic Balancing

[hallra]

Thanks, John, for the reply, it's interesting every time to see what your thoughts are...

I presume to check that the pump is on the flow side of the boiler is by feeling where the heat goes...
Whenever I've checked, the first pipe to give off heat is the one below the pump, which should be correct one as the arrow on pump is pointing upwards and the arrows on the two-way valves are pointing away from the pump...

Getting rid of air is a questionable one as I can't find any air anywhere but always have a suspicion that air is trapped somewhere.
- One interesting thing I have seen time to time with the new gauge below the expansion tank is that, when I let the system cool down I see the pressure drop on the gauge, I then top the system back up, it will rise rapidly, going from say 0.5bar to 1.5bar, then I turn the system on to heat for a bit, stop it, let it cool down and then again I see the pressure drop to 0.5bar, then I top up again... I had to repeat this process numerous times on Thursday (after putting the ABV back and changing the TRV bodies) till eventually it stopped occurring... However, yesterday when playing around, a few times I let the system cool down to then find myself with a pressure drop... which I then filled again... repeating a few time... It got me questioning whether the filling loop which is using 10mm flexible braided hose, is too narrow and perhaps is introducing air into the system... Being that the water entering under 3bar of pressure is separating as it is forced through the 10mm hose... I'm sure I've read that this can happening...


When you say about up/down radiators not heating together, I'm not sure if that is the case or maybe I have described it incorrectly...

Both upstairs and downstairs are heating up, just I would describe it as not in balance... That is that the radiators don't have equal heat on flow/return and some struggle to have heat when the pump is on lower settings...
- I thought that is a typical description of unbalanced radiators... Have I misunderstoood?

FYI, here are some numbers I took yesterday when trying to manually balance with the pump on:
- I think the system had been heating around 10/15 mins, I didn't note it down, I can't remember which pump setting I had it on, possibly CC at 65%, I would need to repeat to be 100%.

Isolating valves either side of PRV... What valves, there aren't any that I see... I also believe that have isolating valves should not be either side to ensure the PRV isn't accidently isolated... Can you point out to me what you are seeing?
- I was considering putting a service valve below the expansion tank to allow correct testing of the air side of expansion vessel.

When I pressure tested the air side of the expansion vessel, I had to drain down the water to isolate it...
- Altecnic (Caleffi) tech support advised:

Pressure settings: 1.6bar air side & 1.4bar system side.

I asked about the fact that the pressure gauge doesn't go up with heat and got told that was correct behaviour...

I asked to make sure gauge & vessel were the right way up.

I also asked about air in the system.

It looks like at some point, the conversation stopped, I probably got distracted and forgot about it... So if need be I can go back to them to ask further questions...


How do I check the MVs are opening fully?

- They are both definitely opening, % wise, no idea how to check...

- However, I noticed yesterday that the MV to upstairs was buzzing, which in my mind is an indication that it is starting to fail. In the past one of the MVs failed, I think it was the upstairs previously as well... I know the downstairs one was plumped in backwards, which I only noticed, had corrected in Oct 2018.
- If you think it is wise, I can always do as I said previously, which is take out one of the MVs, so only have one MV for the whole house.... Guess it would then rule out a number of potential issues... would require a little change to the pipework...


Ooohhh, I like your idea of isolating each radiator one at a time, to bleed them... Tomorrow, I will do this, record the numbers and we can discuss results...

- I do remember watching a youtube video which someone did this... What they also did was keep the fill loop open and controlled via PRV, they then isolated each radiator, opening the lockshield drain off to flush air that was trapped out... I actually bought a PRV to do this very thing. However, I didn't actually implement this as I hadn't all the connections to implement and then again got distracted... So, if needed, can do this later...

Anyway, now I'm waffling on, so thanks for the advice, I'll come back to you tomorrow.

 

[hallra]

This is a report that is produced by the balancing softwere after the balancing process is complete, might be some useful information in this?

 

[John.g]

Thanks, John, for the reply, it's interesting every time to see what your thoughts are...

I presume to check that the pump is on the flow side of the boiler is by feeling where the heat goes...
Whenever I've checked, the first pipe to give off heat is the one below the pump, which should be correct one as the arrow on pump is pointing upwards and the arrows on the two-way valves are pointing away from the pump...

Getting rid of air is a questionable one as I can't find any air anywhere but always have a suspicion that air is trapped somewhere.
- One interesting thing I have seen time to time with the new gauge below the expansion tank is that, when I let the system cool down I see the pressure drop on the gauge, I then top the system back up, it will rise rapidly, going from say 0.5bar to 1.5bar, then I turn the system on to heat for a bit, stop it, let it cool down and then again I see the pressure drop to 0.5bar, then I top up again... I had to repeat this process numerous times on Thursday (after putting the ABV back and changing the TRV bodies) till eventually it stopped occurring... However, yesterday when playing around, a few times I let the system cool down to then find myself with a pressure drop... which I then filled again... repeating a few time... It got me questioning whether the filling loop which is using 10mm flexible braided hose, is too narrow and perhaps is introducing air into the system... Being that the water entering under 3bar of pressure is separating as it is forced through the 10mm hose... I'm sure I've read that this can happening...


When you say about up/down radiators not heating together, I'm not sure if that is the case or maybe I have described it incorrectly...

Both upstairs and downstairs are heating up, just I would describe it as not in balance... That is that the radiators don't have equal heat on flow/return and some struggle to have heat when the pump is on lower settings...
- I thought that is a typical description of unbalanced radiators... Have I misunderstoood?

FYI, here are some numbers I took yesterday when trying to manually balance with the pump on:
- I think the system had been heating around 10/15 mins, I didn't note it down, I can't remember which pump setting I had it on, possibly CC at 65%, I would need to repeat to be 100%.

View attachment 37039

Isolating valves either side of PRV... What valves, there aren't any that I see... I also believe that have isolating valves should not be either side to ensure the PRV isn't accidently isolated... Can you point out to me what you are seeing?
- I was considering putting a service valve below the expansion tank to allow correct testing of the air side of expansion vessel.

When I pressure tested the air side of the expansion vessel, I had to drain down the water to isolate it...
- Altecnic (Caleffi) tech support advised:

Pressure settings: 1.6bar air side & 1.4bar system side.

I asked about the fact that the pressure gauge doesn't go up with heat and got told that was correct behaviour...

I asked to make sure gauge & vessel were the right way up.

I also asked about air in the system.

It looks like at some point, the conversation stopped, I probably got distracted and forgot about it... So if need be I can go back to them to ask further questions...


How do I check the MVs are opening fully?

- They are both definitely opening, % wise, no idea how to check...

- However, I noticed yesterday that the MV to upstairs was buzzing, which in my mind is an indication that it is starting to fail. In the past one of the MVs failed, I think it was the upstairs previously as well... I know the downstairs one was plumped in backwards, which I only noticed, had corrected in Oct 2018.
- If you think it is wise, I can always do as I said previously, which is take out one of the MVs, so only have one MV for the whole house.. Guess it would then rule out a number of potential issues... would require a little change to the pipework...


Ooohhh, I like your idea of isolating each radiator one at a time, to bleed them... Tomorrow, I will do this, record the numbers and we can discuss results...

- I do remember watching a youtube video which someone did this... What they also did was keep the fill loop open and controlled via PRV, they then isolated each radiator, opening the lockshield drain off to flush air that was trapped out... I actually bought a PRV to do this very thing. However, I didn't actually implement this as I hadn't all the connections to implement and then again got distracted... So, if needed, can do this later...

Anyway, now I'm waffling on, so thanks for the advice, I'll come back to you tomorrow.

Expansion Vessel: You say 1.6 bar air side and 1.4 bar water side, the (cold) filling pressure should never be lower than the pre pressure, ideally it should be 0.3 to 0.5 bar higher to give you a little water reserve of 1 to 2 litres which means very infrequent top ups, your pre pressure of 1.6 bar is a little high to do this but I would advise filling to 1.75/1.80 bar when system is cold but no higher as the boiler safety valve lifts at 3.0 bar.
Obviously you have to top up frequently if your are venting rads etc but once finished then if you still have to top up frequently will be indicative of a leak somewhere so when you have the system back to normal keep a eye on this, I would not recommend the fitting of a PRV, sometimes called a auto fill valve as this masks any leakage problems when left open, this is what I was referring to as I thought that you had one fitted to your fill line.
PRV refers to both a Pressure Relief Valve (safety valve) or a Pressure Reducing Valve.
I will attach a little calculation to show the effect of pre and fill pressures on the boiler final pressure.

Re balancing: I would start with all the L.shield valves fully open and then take the DeltaTs on all of them and only throttle in the ones that have the lowest DeltaTs and do it with the pump on PP5.1 setting, maybe that's how you are doing it anyhow, as I said previously once they are all reasonably balanced then you can reduce the pump head as required to give you a greater DeltaT if required. The main thing to avoid is having ALL the L.shield valves throttled as this can cause noisy operation.

You don't really have to do all those individual tests that I suggested above but it would certainly be interesting.

Just thinking again about any other restrictions in your system, I know that you can't test it but is there any possibility that the boiler heat exchanger is partially blocked? the E.vessel is piped in before this, it will affect pump operation if the exchanger is partially blocked, I don't have any experience of sealed heating systems but I might have thought that the E.vessel piping would have connected in just before the pump suction, but again no problem where it is if the exchanger is clean.

Any link to your Air Separator?.

 

[John.g]

This is a report that is produced by the balancing softwere after the balancing process is complete, might be some useful information in this?

Very interesting , I must read it properly later on, is that done with just any one rad on at the time?.

I also read that your boiler has a stainless heat exchanger so that's probably why they claim no bypass required.

 

[hallra]

Expansion Vessel: You say 1.6 bar air side and 1.4 bar water side, the (cold) filling pressure should never be lower than the pre pressure, ideally it should be 0.3 to 0.5 bar higher to give you a little water reserve of 1 to 2 litres which means very infrequent top ups, your pre pressure of 1.6 bar is a little high to do this but I would advise filling to 1.75/1.80 bar when system is cold but no higher as the boiler safety valve lifts at 3.0 bar.
Obviously you have to top up frequently if your are venting rads etc but once finished then if you still have to top up frequently will be indicative of a leak somewhere so when you have the system back to normal keep a eye on this, I would not recommend the fitting of a PRV, sometimes called a auto fill valve as this masks any leakage problems when left open, this is what I was referring to as I thought that you had one fitted to your fill line.
PRV refers to both a Pressure Relief Valve (safety valve) or a Pressure Reducing Valve.
I will attach a little calculation to show the effect of pre and fill pressures on the boiler final pressure.

Re balancing: I would start with all the L.shield valves fully open and then take the DeltaTs on all of them and only throttle in the ones that have the lowest DeltaTs and do it with the pump on PP5.1 setting, maybe that's how you are doing it anyhow, as I said previously once they are all reasonably balanced then you can reduce the pump head as required to give you a greater DeltaT if required. The main thing to avoid is having ALL the L.shield valves throttled as this can cause noisy operation.

You don't really have to do all those individual tests that I suggested above but it would certainly be interesting.

Just thinking again about any other restrictions in your system, I know that you can't test it but is there any possibility that the boiler heat exchanger is partially blocked? the E.vessel is piped in before this, it will affect pump operation if the exchanger is partially blocked, I don't have any experience of sealed heating systems but I might have thought that the E.vessel piping would have connected in just before the pump suction, but again no problem where it is if the exchanger is clean.

Any link to your Air Separator?.

Hi John,

What do you mean by pre-pressure?

From what I understand, are you saying the complete opposite to what Altecnic support line has advised me?

I.E The water side should be 0.3 - 0.5 than the air side?

Why on earth would they tell me the complete opposite?
- Someone on here prior to that, told me to drop the pressure to 1bar on both sides, when that caused problems, I spoke to Altecnic.
- FYI, I have an 18ltr Reflex expansion vessel fitted.
- I understand about the safety valve set at 3bar.
- I also know/understand not to have the Pressure Reducing valve permanently connected, it was for the purposes of driving trapped air out.


- Do you have that calculation to show the effect of pre and fill pressures on boiler final pressure?


Thanks for the advice on the throttling, i'll probably test/record everything, it's useful info.

I would say a good chance that the boiler exchange is partially blocked, as when I flushed all the Rads, it appeared to me that the system never had inhibitor in it.

The boiler was probably never flushed, it took 2 years for the builder (Persimmons) to send someone in to commision the biler and fill in the paperwork... what with that and black water and small metal fillings that came out when I flushed the rads...


Air Separator
-------------

Spirotech Spirovent RV2 Air Separator (Brass) - -: SpiroVent Air Separator 22mm

Spirotech | maximising performance

 

[hallra]

Very interesting , I must read it properly later on, is that done with just any one rad on at the time?.

I also read that your boiler has a stainless heat exchanger so that's probably why they claim no bypass required.

The 'Go Balance' is done with all Rads and H/W off, to take a zero flow reading, then turning one on at a time to do readings and then one where you do reading across two open rads (I think it chooses the two with the highest flow, forget the name they call it)

Once all rad readings, rad specs and room specs are taken, you return to each rad, turning on one at a time, to do the actual balancing.

 

[hallra]

Whilst I remember, a plumber who worked for Persimmons did mention at one point early on that their was something fundamentally wrong with the microbore pipework in the walls. However he would never say what it was as he would be fired.

Never did get to the bottom of it, whether it was really bad or something he just didn’t agree with...

That’s the problem, you cannot really trust anyone or any company.

I now know this plumber quite well and he know longer works for Persimmons, I will try to find out what he was referring to.

 

[John.g]

Hi John,

What do you mean by pre-pressure?

From what I understand, are you saying the complete opposite to what Altecnic support line has advised me?

I.E The water side should be 0.3 - 0.5 than the air side?

Why on earth would they tell me the complete opposite?
- Someone on here prior to that, told me to drop the pressure to 1bar on both sides, when that caused problems, I spoke to Altecnic.
- FYI, I have an 18ltr Reflex expansion vessel fitted.
- I understand about the safety valve set at 3bar.
- I also know/understand not to have the Pressure Reducing valve permanently connected, it was for the purposes of driving trapped air out.


- Do you have that calculation to show the effect of pre and fill pressures on boiler final pressure?


Thanks for the advice on the throttling, i'll probably test/record everything, it's useful info.

I would say a good chance that the boiler exchange is partially blocked, as when I flushed all the Rads, it appeared to me that the system never had inhibitor in it.

The boiler was probably never flushed, it took 2 years for the builder (Persimmons) to send someone in to commision the biler and fill in the paperwork... what with that and black water and small metal fillings that came out when I flushed the rads...


Air Separator
-------------

Spirotech Spirovent RV2 Air Separator (Brass) - -: SpiroVent Air Separator 22mm

Spirotech | maximising performance

View attachment 37045

The pre pressure is the air pressure in the E.vessel with no pressure on the water side, or with the E.vessel unconnected. The filling pressure is then the pressure after admitting water to it with boiler and system contents cold.
I have posted the spreadsheet above, "Expansion vessel calculation extract", you can put your own figures into it and see what the final pressure will be, for example with a 18 ltr E.vessel and a pre pressure of even 1.6bar and a fill pressure of 2bar and based on a expansion vol of 2.5 litres then the final pressure would be 2.6 bar.
I would suggest, when you get a chance, to drop the pre pressure to 1 bar and and set the fill pressure to 1.5 bar and you will have a nice little water reserve and a very low final pressure.

Maybe the guys at Altecnic who gave you that great advice were from Cork??.

With a 18 litre E,vessel, a 1.0 bar pre pressure and a 1.5 bar filling pressure will give you a water reserve of a very nice 3.6 litres and a final pressure of only 2.03 bar.
That is is one very big advantage of a external E.vessel as you cannot oversize it but the integrated ones in the boilers are only 8 litres or so.

What problems did dropping the pre and filling pressure to 1.0 bar cause?? was it pump noise?, if so then maybe leave the pre pressure at 1.6 bar and the fill pressure at 2.0 bar, but just observe what the final pressure is when everything is nice and hot.

 

[hallra]

Thanks, looks like I’ve got my hands full tomorrow...

If I’m going to do the expansion vessel pre-Pressure, I might as well add a service valve:

https://www.NoLinkingToThis/p/tesla...T5Z70ngv-_vkydQXFlhoCc34QAvD_BwE&gclsrc=aw.ds

And whilst I’m doing that, seeing I would drain down the system, what do you think about moving the expansion vessel to the pipework before the pump?
- just in case a partial heat exchange blockage?
- I’ve checked the boiler install instructions put the expansion vessel before the pump and with the pipe layout wouldn’t be to much to move it over...

 

[John.g]

Thanks, looks like I’ve got my hands full tomorrow...

If I’m going to do the expansion vessel pre-Pressure, I might as well add a service valve:

https://www.NoLinkingToThis/p/tesla...T5Z70ngv-_vkydQXFlhoCc34QAvD_BwE&gclsrc=aw.ds

And whilst I’m doing that, seeing I would drain down the system, what do you think about moving the expansion vessel to the pipework before the pump?
- just in case a partial heat exchange blockage?
- I’ve checked the boiler install instructions put the expansion vessel before the pump and with the pipe layout wouldn’t be to much to move it over...

I think some plumber here at home told me that he was informed that it is'nt legal here at any rate to fit a isolating valve, I presume because it can be left shut but if it is illegal it seems a bit daft as dozens of E.vessels fail due to a ruptured bladder, the auto fill valve or the house holder re pressurizes to 1 bar and as soon as the water heats up it lifts the boiler safety valve as there is now no expansion volume in the "broken" E.vessel.

Re relocating the E.vessel piping, on reflection that might not be a great idea because if there is a exchanger partial blockage then it just might cause a very low water pressure in the exchanger which could lead to other problems.

 

[hallra]

Looks like the service valve has a anti tamper device to stop accidental closure by householder:

TeslaUK launches new Expansion Vessel Service Valve - Installer Online

So guess that allows it to be fitted... They would be in a lot of trouble to launch and sale in U.K. if it wasn’t legal...


Are you sure about moving the vessel, as at the moment it isn’t fitted as advised by Glow-worm..

Thought you prevoislusly said it was better to be before the pump 🙂

Even more interesting...

Looks like the install doesn’t conform to current regs anyway...

 

[John.g]

View attachment 37046 Looks like the service valve has a anti tamper device to stop accidental closure by householder:

TeslaUK launches new Expansion Vessel Service Valve - Installer Online

So guess that allows it to be fitted... They would be in a lot of trouble to launch and sale in U.K. if it wasn’t legal...


Are you sure about moving the vessel, as at the moment it isn’t fitted as advised by Glow-worm..

View attachment 37046


Thought you prevoislusly said it was better to be before the pump 🙂

Even more interesting...

View attachment 37047

Looks like the install doesn’t conform to current regs anyway...

I'd say that isolation valve looks ok so its probably legit.

My only concern re moving the E.vessel pipe is that by doing so it may create a low pressure zone before exchanger (if exchanger plugged) and cause air to be drawn further back but if you are happy to relocate it then fine but leave it so as that it can be put back easily in its original location

 

[hallra]

You are like me John, don’t sleep well at night...

Been doing some reading on expansion vessels and pressures...

If I don’t move the vessel, then a different pressure calculation is needed to take into account that vessel is down stream of the pump...

https://www.caleffi.com/sites/default/files/file/01079_en.pdf
- They also do a service valve...

Plus another adjustment is required as the Expansion vessel is on the first floor and boiler is on ground, though 1.5m off the ground.

If you look at the earlier photo of the pipework, it wouldn’t be too difficult as the return and flow pies from the boiler are next to each other (A & B£, so it wouldn’t take too much to shift from the vessel from return to flow...

 

[hallra]

Damn it...

That Caleffi link I sent you states installation of the vessel should be on the return pipe:..

So now conflicting advice...

So stick or twist.. arrggghhh

Another website:

Sizing of expansion vessels

 

[John.g]

Damn it...

That Caleffi link I sent you states installation of the vessel should be on the return pipe:..

So now conflicting advice...

So stick or twist.. arrggghhh

Another website:

Sizing of expansion vessels

I wouldn,t get too hung up on that sizing, just remember to add the static head from the the E.vessel to the boiler safety valve, in your case ~ 0.25 bar. ( I should have twigged that the boiler wasn't "upstairs").
If I use 2.o litre as your expansion volume (it won't be more with only 8 rads and a gas fired boiler of contents ~ 2 litres) then if you leave the pre pressure as is @ 1.6bar, fill pressure of 2.0 bar you will end up with a reserve of 2.4 litres & a final pressure of 2.4 bar...+ 0.25 bar static head = 2.65bar at the boiler, still OK . If you wish you can drop the pre pressure to 1.0 bar, fill pressure of 1.5bar gives a reserve of 3.3 litres & a final pressure of 2.13bar...+0.25 bar static head = 2.38 at the boiler. Generally the higher the final pressure from a pump point of view the better as long as it doesn't exceed say 2.6/2.8 bar at the boiler.
I have changed several relations E.vessels over the years & all of them were tied in u/stream (before) of the pump, a few of them had the pump on the boiler return (pumping into the boiler) but the E.vessel was still piped in U/stream (before) of the pump.
I have a vented system with a combined vent & cold feed.

The logic is I suppose that if tied in before the pump then the pump suction will be at the E.vessel pressure and the pump discharge will be at the pump head + the E.vessel pressure, if fitted after the pump, the pump discharge will be at the E.vessel pressure but the pump suction will be at the pump head minus the E.vessel pressure.

I would suggest, for the moment at any rate, to leave the E.vessel as is, reduce the pre pressure to 1.0 to 1.2 bar, add 0.5 bar for the fill pressure giving either 1.5 or 1.7 bar fill pressure and see how you go.
When the boiler is then fully heated up with everything on, read off the final pressure and add 0.25 bar to it to give you the pressure at the boiler, you may then decide to up the pressures a little.

Must go for a walk now.

Edit: you said that when you dropped the pre and fill pressure to 1 bar that you had problems.... what kind of problems? ( I asked this already), when both these pressures are the same and if you have a restriction anywhere then the E.vessel & pump suction can fall to zero or near it and create pump problems.

 

[hallra]

Hey, just woke, it’ll be a few hours before I’ll be ready to roll up my sleeves.

I’ve read what you have said above and have decided the plan is:

Shut all off
Empty enough water to remove expansion tank to fit service valve.
Set pre pressure to 1.2 bar.
Fill pressure 1.7 bar.
Remove air as much as possible.
Heat system.
Close all rads and then open up each rad one by one to force trapped air out, taking readings as I go.

One final thought before I start my plan... do I change the fill loop hose & connectors from 10mm to 22mm, to smooth the water flow coming in? Or you think having 10mm will make little difference? Sound wise it sounds like there is a lot of turbulence when adding water...

What you think?

 

[John.g]

Hey, just woke, it’ll be a few hours before I’ll be ready to roll up my sleeves.

I’ve read what you have said above and have decided the plan is:

Shut all off
Empty enough water to remove expansion tank to fit service valve.
Set pre pressure to 1.2 bar.
Fill pressure 1.7 bar.
Remove air as much as possible.
Heat system.
Close all rads and then open up each rad one by one to force trapped air out, taking readings as I go.

One final thought before I start my plan... do I change the fill loop hose & connectors from 10mm to 22mm, to smooth the water flow coming in? Or you think having 10mm will make little difference? Sound wise it sounds like there is a lot of turbulence when adding water...

What you think?

No, I don't think it will make any difference whatsoever, the noise that you are hearing I would think is from the throttling effect across the fill valve in reducing the mains pressure (4 or 5 bar?) down to 1.5 bar or whatever. I hear the same noise when topping up the relations systems.

 

[hallra]

Ok, fair enough, will skip.

What you thoughts of changing the air side pressure without drain down?

I was reading something last night that it might be possible, but the calculations change or is it not a wise thing to do?
- Obviously, skipping a drain down saves me adding more inhibitor.

Let me know your thoughts?

Alternative, would be to pull a vacuum, but i've never done it before. Guessing to risky for a DIYer?
- Just remember, it a pain in the arse to disconnect the expansion tank from the pipework, due to a solid manifold connector, I literally have to dismantle. - Another reason for adding a service valve.

Thoughts?

 

[John.g]

Ok, fair enough, will skip.

What you thoughts of changing the air side pressure without drain down?

I was reading something last night that it might be possible, but the calculations change or is it not a wise thing to do?
- Obviously, skipping a drain down saves me adding more inhibitor.

Let me know your thoughts?

Alternative, would be to pull a vacuum, but i've never done it before. Guessing to risky for a DIYer?
- Just remember, it a pain in the arse to disconnect the expansion tank from the pipework, due to a solid manifold connector, I literally have to dismantle. - Another reason for adding a service valve.

Thoughts?

OK then, I think your happy/sure that the present Pre pressure was/is 1.6 bar.
Fire up the boiler with all systems full open including hot water, turn the cylinder stat fully up to ensure the MV valve doesn't close and ditto with any room stats, when you are happy that the system contents are up to temperature, check and note down the E.vessel pressure and then just open the fill valve carefully and increase the pressure to say 2.0/2.1 bar, this will give you 2.25/2.35 bar at the boiler.

 

[hallra]

Before I do so, is that a safe thing to do in terms of protecting the system & boiler, is running that high ok?
- I presume it is as you are a cautious Guy...

I’m guessing it is fine as it would only be a max 2.3/2.4 at boiler, plus the PRV opens at 3 bar for ultimate protection.
Only question would be is would it be making the boiler work too hard.

Sorry for all the questions.