UFH Issue

[pepelepeu]

Hello

 

I wonder if I could ask for help with regard to my UFH system.

 

I have a NIBE ASHP supplying my UFH and hot water. I have a lot of air in the system (very audible as it passes through the pump) and despite the fitters coming back on several occasions it has not been cured. Added to this my expansion vessel keeps returning to zero pressure and I have to top it up almost on a daily basis. When I tap the red expansion tank

it hs a hollow sound at the bottom and a dull sound at the top. My limited knowledge makes me think it should be the other way around with liquid at the bottom and air at the top?

 

One final thing is that one of the loops is showing dirty water in the manifold flow glass, all the others are clean. is there an issue here too?

 

Any help would be appreciated as my installer is not curing the problem and possibly fobbing me off!

 

[ProDave]

How old is the system?  did you see HOW he bled the UFH pipes? (tip is usually involves the use of a hose pipe)

 

If a new install it is clearly not right so keep pestering him.  

[Post and beam]

Do you have a leak? Dirty water sounds a little worrying

[Dave Jones]

are there any rads as well ? could explain dirty water ....

 

Bleeding loops, especially long ones, takes a good while. It's an all day job on our last place as there was a lot.

[Temp]

8 hours ago, pepelepeu said:

Added to this my expansion vessel keeps returning to zero pressure and I have to top it up almost on a daily basis.

 

If you have to keep putting air into the expansion vessel then it's faulty.  I wonder if the air you are putting into the expansion vessel is escaping into the system. 

 

 

[pepelepeu]

On 06/04/2023 at 12:37, ProDave said:

How old is the system?  did you see HOW he bled the UFH pipes? (tip is usually involves the use of a hose pipe)

 

If a new install it is clearly not right so keep pestering him.  

The system is 16 months old. The system has automatic bleed valves and I have never seen them use a hose....

[pepelepeu]

On 06/04/2023 at 13:03, Post and beam said:

Do you have a leak? Dirty water sounds a little worrying

There is nothing obvious to say I have a leak but I have solid screed floors.

[pepelepeu]

On 06/04/2023 at 14:36, Dave Jones said:

are there any rads as well ? could explain dirty water ....

 

Bleeding loops, especially long ones, takes a good while. It's an all day job on our last place as there was a lot.

Hi 

no we only have the underfloor loops.

[pepelepeu]

Many thanks for your comments. I'm trying to organise for them to return so the more information I can glean the better!

[pepelepeu]

Has anyone any thoughts on the expansion vessel that is hollow at the bottom and solid sounding at the top?

[Nickfromwales]

On 06/04/2023 at 12:01, pepelepeu said:

Added to this my expansion vessel keeps returning to zero pressure and I have to top it up almost on a daily basis. When I tap the red expansion tank

Ok.

I assume you mean the system pressure, indicated on the gauge at the filling loop ( the bit you use to top it up ) keeps returning to zero and not the pre-charge in the gas side of the expansion vessel?

1 hour ago, pepelepeu said:

Has anyone any thoughts on the expansion vessel that is hollow at the bottom and solid sounding at the top?

This is probably not how things are. Does the water enter into the bottom of the expansion vessel ( EV )? Is it mounted vertically?

[Nickfromwales]

On 06/04/2023 at 12:01, pepelepeu said:

and I have to top it up almost on a daily basis

Where is the PRV ( pressure relief valve ) located? And where does it discharge? It may be part of the group where the topping up aka filling loop is mounted ( as these usually are made up of a filling loop / pressure gauge / PRV / EV as a "pressurisation" kit.

Topping up daily shows a huge problem / leak. I'd say one loop is leaking ( without first knowing if the PRV is passing ( allowing water to escape )).

[pepelepeu]

On 08/04/2023 at 23:04, Nickfromwales said:

Ok.

I assume you mean the system pressure, indicated on the gauge at the filling loop ( the bit you use to top it up ) keeps returning to zero and not the pre-charge in the gas side of the expansion vessel?

This is probably not how things are. Does the water enter into the bottom of the expansion vessel ( EV )? Is it mounted vertically?

Yes Nick, it enters at the bottom and is mounted vertically. I've hopefully attached an image!

[pepelepeu]

On 08/04/2023 at 23:12, Nickfromwales said:

Where is the PRV ( pressure relief valve ) located? And where does it discharge? It may be part of the group where the topping up aka filling loop is mounted ( as these usually are made up of a filling loop / pressure gauge / PRV / EV as a "pressurisation" kit.

Topping up daily shows a huge problem / leak. I'd say one loop is leaking ( without first knowing if the PRV is passing ( allowing water to escape )).

I hope the photo previously sent has all these questions answered Nick? The PRV has recently been replaced.

[Nickfromwales]

1 hour ago, pepelepeu said:

I hope the photo previously sent has all these questions answered Nick? The PRV has recently been replaced.

If you are topping up daily, you need to stop doing so. Use the immersion for hot water and find the leak. Your installer is avoiding the elephant in the room, eg where the feck is all the water going?

You can start investigations by isolating one UFH loop at a time, re-pressurise, and check the pressure 24 hrs later. When you stop seeing the drop, you've found the offending loop.

If you go through them all with no change, the leak is elsewhere.

Can you see evidence of a leak anywhere?

[Temp]

+1

 

If you have to keep topping up the system pressure that suggests water is escaping somewhere. Either out of the PRV or a leak.

 

I know you said the PRV has been replaced but PRV can be a bit temperamental. If they let water out once for any reason they can often start dripping or letting water out at less than the rated pressure. Perhaps put a plastic bag over the outlet pipe for 24 hours and see if it collects any water.

 

If its not the PRV I think you may need to start isolating and pressure testing parts of the system to narrow down where the leak might be. 

 

 

[Marvin]

11 minutes ago, Temp said:

PRV's can be a bit temperamental.

Hi @pepelepeu

 

Yes, a bit of grit or a frequent flow of water out of the overflow can scale the PRV components.

 

As the water in your system heats up it expands and need somewhere to go otherwise the pressure will rise and water will be released by the PRV. When the water temperature reduces and the volume of the water shrinks the correct pressure will be lost. Now you have to fill it up again... 

 

When filling up the system to the correct pressure does the pressure gauge rise quickly to the correct pressure or slowly? The reason I asked is because the top of the pressure vessel needs to be pressurised, by pumping air in, to the level required to work properly. 

 

If the air pressure is too low the expansion tank will fill up the available space for expansion (the resistance to pressure being so low) when setting the water pressure side.

 

If the pressure is too high the pressure vessel will not allow any room for expansion before the pressure forces the water through the PRV.

 

Worth checking the settings.

 

Good luck

 

Marvin

[pepelepeu]

18 hours ago, Nickfromwales said:

If you are topping up daily, you need to stop doing so. Use the immersion for hot water and find the leak. Your installer is avoiding the elephant in the room, eg where the feck is all the water going?

You can start investigations by isolating one UFH loop at a time, re-pressurise, and check the pressure 24 hrs later. When you stop seeing the drop, you've found the offending loop.

If you go through them all with no change, the leak is elsewhere.

Can you see evidence of a leak anywhere?

Thanks Nick I'll start isolating one at a time. There is no evidence of a leak. I will isolate the dirty water loop first.

[pepelepeu]

18 hours ago, Temp said:

+1

 

If you have to keep topping up the system pressure that suggests water is escaping somewhere. Either out of the PRV or a leak.

 

I know you said the PRV has been replaced but PRV can be a bit temperamental. If they let water out once for any reason they can often start dripping or letting water out at less than the rated pressure. Perhaps put a plastic bag over the outlet pipe for 24 hours and see if it collects any water.

 

If its not the PRV I think you may need to start isolating and pressure testing parts of the system to narrow down where the leak might be. 

 

 

Thnaks Temp, I'll try out the plastic bag ides...

[pepelepeu]

18 hours ago, Marvin said:

Hi @pepelepeu

 

Yes, a bit of grit or a frequent flow of water out of the overflow can scale the PRV components.

 

As the water in your system heats up it expands and need somewhere to go otherwise the pressure will rise and water will be released by the PRV. When the water temperature reduces and the volume of the water shrinks the correct pressure will be lost. Now you have to fill it up again... 

 

When filling up the system to the correct pressure does the pressure gauge rise quickly to the correct pressure or slowly? The reason I asked is because the top of the pressure vessel needs to be pressurised, by pumping air in, to the level required to work properly. 

 

If the air pressure is too low the expansion tank will fill up the available space for expansion (the resistance to pressure being so low) when setting the water pressure side.

 

If the pressure is too high the pressure vessel will not allow any room for expansion before the pressure forces the water through the PRV.

 

Worth checking the settings.

 

Good luck

 

Marvin

Hi Marvin  thanks for this knowledge. When I top up it is very quick, probably no more than 5 seconds.This morning I went in and the air circulating around the flow pump was very noisy.

[Marvin]

Hi @pepelepeu

 

 

 

Judging from my experience the Expansion vessel is not working properly. Our ASHP system runs at 2 bar so the red line is about right.

 

Is the valve on the pipework which allows the pressure to expand the vessel  OPEN?  looks closed to me. That's the one to the left of the PRV in your photo. 

 

 

Should it not be like this?

 

 

 

and not this 

 

 

Good luck 

 

Marvin

 

[pepelepeu]

19 hours ago, Marvin said:

Hi @pepelepeu

 

 

 

Judging from my experience the Expansion vessel is not working properly. Our ASHP system runs at 2 bar so the red line is about right.

 

Is the valve on the pipework which allows the pressure to expand the vessel  OPEN?  looks closed to me. That's the one to the left of the PRV in your photo. 

 

 

Should it not be like this?

 

19 hours ago, Marvin said:

 

 

and not this 

 

 

Good luck 

 

Marvin

 

Yes it is closed Marvin, always has been...unless I use it to top up of course!

[Nickfromwales]

23 hours ago, pepelepeu said:

This morning I went in and the air circulating around the flow pump was very noisy.

Ok. There is defo a serious leak here as the system is part-draining down and is sucking air back in through the automatic air bleed vents ( they work both ways when there isn't any water inside ).

Stop using the heating system immediately, as you're just constantly refilling with fresh oxygenated water which is corroding everything ferrous, hence the dirty look to the water.

Get the plumber back in immediately to fix, give this to him in writing, text / email / WhatsApp and tell him either he fixes this, or you'll get someone else at his expense.

[pepelepeu]

2 hours ago, Nickfromwales said:

Ok. There is defo a serious leak here as the system is part-draining down and is sucking air back in through the automatic air bleed vents ( they work both ways when there isn't any water inside ).

Stop using the heating system immediately, as you're just constantly refilling with fresh oxygenated water which is corroding everything ferrous, hence the dirty look to the water.

Get the plumber back in immediately to fix, give this to him in writing, text / email / WhatsApp and tell him either he fixes this, or you'll get someone else at his expense.

Thank you  Nick Ive contacted him just waiting for a response.

[Marvin]

Hi @pepelepeu

 

5 hours ago, pepelepeu said:

Yes it is closed Marvin, always has been...unless I use it to top up of course!

I think it should be open. That is the black valve on the left ( I assume there are 2 valves and not just a bad photo).