Search the forum,

Discuss Heating Expansion Vessel in the Plumbing Jobs | The Job-board area at PlumbersForums.net

Messages
111
Hi Forum,

I recently fitted a new Grundfos pump on my sealed heating system.

For some unknown reason I was having trouble getting rid of air, I would empty radiators with air returning again later, I've been repeating the task for over a week.

Last night, I was reading up on what might cause air to get into a sealed system, the only thing I found was issues with the expansion vessel...

Today, I checked the air valve on the expansion vessel, depressing it let out air, no water...

I've then depressured the heating system, put a pressure gauge on the expansion vessel, to find it had n0 pressure, it was empty...

i've repressured to 1.5bar, the factory pre install pressure, to find 1/2hr later that the pressure has dropped 1/4 bar.

I presume the vessel has gone and needs replacing?

What would you recommend as a good make of heating expansion vessel?
- There are a lot of different makes out there, the current being a Altecnic (ERES), but that's lasted only 3 years.

thanks in advance
 
Might just be the Schraeder valve. Boiler off, remove old valve and get a matching new one from Halfords (there are two types - different lengths). Alternatively buy both and throw away ones not needed.
 
As above ^^
If the vessel diaphragm had gone you would get water always when you press the Schraeder valve open.
So looks like the valve is just faulty.
Double check there is still only air coming out and then buy a schraeder valve if you want to save money.
 
Hi Forum,

I recently fitted a new Grundfos pump on my sealed heating system.

For some unknown reason I was having trouble getting rid of air, I would empty radiators with air returning again later, I've been repeating the task for over a week.

Last night, I was reading up on what might cause air to get into a sealed system, the only thing I found was issues with the expansion vessel...

Today, I checked the air valve on the expansion vessel, depressing it let out air, no water...

I've then depressured the heating system, put a pressure gauge on the expansion vessel, to find it had n0 pressure, it was empty...

i've repressured to 1.5bar, the factory pre install pressure, to find 1/2hr later that the pressure has dropped 1/4 bar.

I presume the vessel has gone and needs replacing?

What would you recommend as a good make of heating expansion vessel?
- There are a lot of different makes out there, the current being a Altecnic (ERES), but that's lasted only 3 years.

thanks in advance
What boiler make and model boiler do you have?
 
Hi,

I got hold of the plumber who had previously worked on the property, he reminded me the vessel was undersized...
With that, the issues I had and I don’t trust the builder (Persimmons), I decided safest bet was to replace the vessel.

I bought a Altecnic Reflex 18L, which looked like the replacement for the Altecnic Eres.

When I took the old vessel off, it was badly chocked up inside with a lot of black soot, which for a 3 yr old system, very worrying.

- I had ran Adey Cleaner and add inhibitor after pump install.

Water came out pretty clear when draining, I don’t think I need to run more cleaner through system again.


Would people agree??


@Harvest Fields - Boiler is a Glow-Worm Ultracom 24HXI
 
Hi,
I got hold of the plumber who had previously worked on the property, he reminded me the vessel was undersized...
With that, the issues I had and I don’t trust the builder (Persimmons), I decided safest bet was to replace the vessel.
I bought a Altecnic Reflex 18L, which looked like the replacement for the Altecnic Eres.
When I took the old vessel off, it was badly chocked up inside with a lot of black soot, which for a 3 yr old system, very worrying.
- I had ran Adey Cleaner and add inhibitor after pump install.
Water came out pretty clear when draining, I don’t think I need to run more cleaner through system again.

Would people agree??

@Harvest Fields - Boiler is a Glow-Worm Ultracom 24HXI
Yes it should be fine, it is just the rubber breaking down.

One thing - the vessel charge pressure should equal the cold fill pressure of the system. For most 1 - 2 story dwellings a pressure of 1bar (10M head) is more than enough. The higher the pressure used the bigger the vessel needs to be to accommodate the expansion of the system.
 
Hi Chris,

I have a three story house, with the pressure gauge preset (Red needle) by the original installer at 1.5bar.

The 18L expansion vessel is factory set at 1.5bar.

How can I educated myself on how to calculate the head of my system?

Is head the distance from the pump (top/centre/bottom) up to the top of the highest radiator?

Or

Is it from bottom of lowest radiator at bottom of house up to the top of the highest radiator?

Or

Something else entirely?


I’ve looked around for a definite answer, but haven’t found :(
 
So gauge will need to show a pressure equal to the head of water required for water will reach the pipe work & rads on the top floor. Taking that the normal story height is less than 3M it would need to show a minimum of say 0.5 bar (0.1bar = 1M head), in practice most people would probably charge it to 1bar to provide a reserve of water incase of small leaks / weeps.
The gas charge in the vessel should be adjusted to match the cold fill water pressure above it.
So reduce the factory charge down to 1bar if it is 1.5bar.
 
Our total height is approx 9m, so from the equation you give, 1bar is the correct pressure.

So why was the guage set to 1.5bar and the plumber I had in to install the pump last week,
(he sub contracts for the builder) told me 1.5bar was correct?

Could it be the house has microbore throughout?,

Sorry for all the questions, I’m trying to educate myself, to understand for future?

Is there a consequence of having the pressure too high/too low, 1.5bar compared to 1bar?
 
Your expansion vessel & gauge are on the middle floor of your house so you only need to put enough water into the system for the water to get to the top floor.
If as suggested you put 1bar on a gauge on the middle floor but had gauges on the top & ground floors they would read = ground 1.3bar but only 0.7bar on the top floor as you have to contend with gravity.

Why did he say 1.5bar ? cos they don't understand & someone told them once that 1.5 is fine. Nothing to do with what system you have.
Consequence of over pressure is reduced capacity of the expansion vessel, system put under more strain than it needs to be so increased risk of leaks & leak rate will be quicker.
Under pressure - if it drops so low that there is no water in the top of the rads on top floor they will be cold as the water is transferring the heat.
 
Hi Chris / Forum,

I've been having a few strange sypmtoms since lowering the air pressure in the vessel & the water pressure on the CH side down to 1 bar.

Not too sure what is going on, so will list what I did and what happened.

1) I depressurised the water side to zero pressure.

2) Checked the vessel pressure, it read 2 bar.
- Weird, why did it read 2 bar, when it had been pre-charged at 1.5bar. (Before install i checked it, it was 1.5bar)

3) Reduced air pressure down to around 1 bar, decided my standing foot pump pressure guage was hard to read 1Bar accurately, and worried about the 2 bar reading, so went and bought a draper digital tyre guage, to get more accurate reading.

4) Digital guage said vessel's air pressure was not 1bar, but 1.3bar, let out more air to get to 1bar.

5) Added automatic air bleeds to serveral radiators, I had ordered these prior to buying vessel, decided to use them because I had them to hand..

6) Added Adey MC1+ inhibitor.

7) Added water to CH system, to bring pressure guage to 1 bar.
- Turn off system/pump, expeled air manually where I could, topped up water, repeat, till all radiators appear to have no air in them.

8) Turned on heating, watched pressure guage, pressure never increased...

9) Notice upstairs towel rail with autovent fitted, not fully expelling air, turned off system/pump, manually undo autovent and expell air, topped up water, turned system/pump on.
- Guessed this was reason pressure guage didn't move.

Stopped at this point and left alone...

All this week:

1) Pressure guage never moves...

2) Hearing gurgling noises and water movement in radiators with autovents.
- The same noice issues heard before I put on the new vessel...


So I'm concerned with:


1) Why isn't pressure increasing when system heats up.
- No problems with guage if water is added to system.
- When system was pressure to 1.5bar previously, pressure was increased as system heated.

2) Is the air pressure correctly set in the vessel, have I somehow screwed it up.

3) Why am I still unable to vent all the air from radiators, even with autovents added?

I must admit I'm really confussed with what is going on as it doesn't seem logical to me...
- I've dealt with lots of several heating systems in the past, but never had these types of issues, though it is my first time with a sealed system.

Thanks all in advance.

Richard.
 
Hi Richard
What is going on, at least with the system pressure / vessel, is that they are working as they should. You have set up the pressure of the gas in the vessel to equal the cold system pressure, as soon as there is an increase in the water volume due to heating (expansion) water flows into the vessel & compresses the gas thereby making more room on the water side (system) i.e. the pressure rise is so small you do not see it on the gauge.
The manufacturers of some vessels seem to be putting in more charge than the sates 1.5bar which is why it is so important that engineers check before filling the systems.
If you had left the vessel at it stated check of say 1.5 bar & turned the boiler on the system pressure would of quickly risen up to 1.5 on the gauge then stoped as the gas could only then be compressed & control further rise.
 
Removing air from sealed systems can be problematical as you no longer have an open vent pipe. Micro bubbles can stay in solution for a long time so a lot of people are now investing in air separators. If you still have a 3 peed pump try turning it up & down the speeds to try to help the bibles escape the water velocity.
Not a fan of the auto rad air vents I think I tried one once & it was more trouble than it was worth, could be allowing air in if oder negative pressure.
What do others think are they good or bad??
 
Hi Chris,

I was reading everywhere that the pressure gauge goes up when heat expands the water and that made sense because volume increases.

I'm guessing that the air in the vessel can compress so far without the water pressure increase, which is the whole point of the vessel.... That makes sense.
- though not sure why at 1.5bar, the water pressure increased by a 1/4 - 1/2 bar when heating on.


I think I'll remove the autovents because I can't manually tell if air has been expelled, I have to trust.
- The air appears to gurgle/bubble more around the system at night.
- Starting last night, I'm getting a low level humm noise on the radiators with the autovents, which isn't good.
 
Maybe I need to add an Air Sperator to my system, what is a good make/model to buy and where on the circuit should it be added?

Just to make sure I haven't got one already fiited, I'll take a couple of photos, as there are two manual air vents near the pump/two way values.
- I don't think they are air sperators, but want to check.
 
IMG_20181207_161742.jpg
IMG_20181207_161722.jpg


Na, these are just manual air vents...
 
image.jpg


This air vent is leaking...

I’m guessing this is the source of the air in the system?

Can I pull a vacuuum to change this without draining the system again?

Could I change it to an air separator or wrong location / still need an air vent here?

View attachment 35797
 
Alright, I got it wrong :)

The vent that is leaking is an ESI Automatic air vent, it leaks when the internals get gunk blocking the float resealing once air has been let out.
- Not sure if when it can't reseal whether more air can be sucked in. I will try to service, else replace it... Not something I'll look forward to, as it will mean another drain down, wasting more inhibitor :(

Will do some more research to compare an air separator to an automated air vent...
 

Reply to Heating Expansion Vessel in the Plumbing Jobs | The Job-board area at PlumbersForums.net

Creating content since 2001. Untold Media.

OFFICIAL SPONSORS

OFFICIAL SPONSORS

Back
Top
AdBlock Detected

We get it, advertisements are annoying!

Sure, ad-blocking software does a great job at blocking ads, but it also blocks useful features of our website. For the best site experience please disable your AdBlocker.

I've Disabled AdBlock