Air pulled in the Heating system / life lesson

traume

Summary:
In the heating period oil boiler would stall every 2-3 days and i have to bleed the system to make it work again. The only way how to do it is by either bleeding through the circulation pump (see attachment) or by bleeding at Non-return valve as air is present only in the feeding pipe and very rearly it would get to the main loop. Oil boiler works until I believe burner thermostat kicks in and shuts it down.

Heating system:
Warmflow KP90HE oil boiler (attachment), Autotopup system , 3 zones (Ground floor, First floor and Hot water), feeding valve always opened.

A bit of context around:
May 2019 we got Warmflow KP90HE oil burner installed. This part is absolutely our fault as we picked the cheapest option (1500e difference for the same boiler) was promissed warranty and service, but now installer is not responding after few visits when he fixed the issue by bleeding the system and saying - everything is going to be okay and warranty by Warmflow is invalid as documentation wasn't filled out properly and final calibration was not done.

In June 2019 we got this issue for the first time, so original installer came over, bled the system and it was working fine until February 2020.
Thats when the hell started, because I quoted around for the burner at the time of buying and we live in quite small village - all other installers refused to come over and check -Blaming our installer.

I don't see any leaks, changed the Automatic Bleeding valve. No idea what to do next. Strangest thing is that if using only the Hot Water zone - issue is not present, but if using any of the other zones, then system will have to be bled every 2-3 days, very rarely once a day.

I understand it is not easy to troubleshoot as issue appears only once in few days.

If anyone from co.Longford reads this and is willing to give it a shot - PM me,
Otherwise - can anyone please point me in the right direction how to proceed from here? I'm a hands on person, but heating is something new for me.

Research in Google mainly shows results for people having air in the main loop and by changing Automatic bleeder most problems are solved, in my case - I have no idea where to look.

Life lesson is: Bought cheap, now have to deal with it myself.

Wearb

Well just to put 1 thing to bed; the oil boiler is unlikely to be the cause of your problems. It is most likely a plumbing issue. So even a new boiler will not cure your problem. An auto fill valve is a cop out by someone who didn't fix a leak or expansion vessel.

How old is the plumbing? Sealed or open vented?

I am unsure of the exact behaviour of your boiler.
When starting from cold with all zones on, give me a step by step report of what happens.

John.G

Can you post a photo of the NR valve and any pressure gauges, also the expansion vessel (if fitted), how many cold water tanks in your attic?.

traume

Wearb wrote: »

Well just to put 1 thing to bed; the oil boiler is unlikely to be the cause of your problems. It is most likely a plumbing issue. So even a new boiler will not cure your problem. An auto fill valve is a cop out by someone who didn't fix a leak or expansion vessel.

How old is the plumbing? Sealed or open vented?

I am unsure of the exact behaviour of your boiler.
When starting from cold with all zones on, give me a step by step report of what happens.

House was built in 2005.
I think it qualifies as open vented, as the valve is all the time opened and it feeds water whenever it needs it.
At the times when bleeding is needed -
Starting cold: Boiler will start, heat up to certain temperature and then will throttle by turning off and on. Time between on and off is very long as believe burner cools down and the starts again. Must be some kind of internal thermo protection.
If it is started, it has never failed, only from the cold start the air is an issue. Could it be because of expansion-contraction? Pressure reduces when cooling down and it pulls air somewhere in?

Regards autofill valve, sorry, i worded it wrong, it is just a non return valve.

traume

John.G wrote: »

Can you post a photo of the NR valve and any pressure gauges, also the expansion vessel (if fitted), how many cold water tanks in your attic?.

1 cold water tank in the attic.
No pressure gauges present for the heating system, the only gauge is on the burner and it is at 3 bar mark all the time.
Expansion vessel is fitted. Not sure how to check if it is functioning.

jimf

if im reading this correctly

it could be a faulty boiler thermostat warmflow stats are known for this intermittent on / off ****

would be suspicious of 3bar on gauge all the time as well could be expansion vessel issue also

traume

jimf wrote: »

if im reading this correctly

it could be a faulty boiler thermostat warmflow stats are known for this intermittent on / off ****

would be suspicious of 3bar on gauge all the time as well could be expansion vessel issue also

Faulty thermostat doesn't explain why it works if I bleed the air from the circulation pump.

3bar gauge is on the burner itself, could it be fuel pressure?

jimf

is this the same plumber who fitted the boiler that told you about warmflow warranty not standing

because if it is its up to him to return the boiler passport to kickstart the warranty for you

this is a cop out on his behalf if so

jimf

traume wrote: »

Faulty thermostat doesn't explain why it works if I bleed the air from the circulation pump.

3bar gauge is on the burner itself, could it be fuel pressure?

certainly 3bar not oil pressure related

any chance circulating pump is faulty

post a pic of gauge

traume

jimf wrote: »

is this the same plumber who fitted the boiler that told you about warmflow warranty not standing

because if it is its up to him to return the boiler passport to kickstart the warranty for you

this is a cop out on his behalf if so

I was going through the paperwork and wanted to make sure I have warranty. Turns out the installer doesn't even have the equipment to perform the final calibration/tests to submit to Warmflow.

My neighbour got the same boiler before me and were convinced she has the warranty. No she doesn't...
I had a great recommendation from her as well before I broke out the news.

I guess I saved over 40%, but now I have no warranty.

jimf

traume wrote: »

I was going through the paperwork and wanted to make sure I have warranty. Turns out the installer doesn't even have the equipment to perform the final calibration/tests to submit to Warmflow.

My neighbour got the same boiler before me and were convinced she has the warranty. No she doesn't...
I had a great recommendation from her as well before I broke out the news.

I guess I saved over 40%, but now I have no warranty.

back in 2019 a grant vortex would have cost you approx. 1350

at the time warmflow would have at guess cost you 1150

no point in beating urself up about it if its a plumbing issue boiler make doesn't come into it

jimf

traume wrote: »

Please see attached,

cant see anything

traume

jimf wrote: »

certainly 3bar not oil pressure related

any chance circulating pump is faulty

post a pic of gauge

Please see attached.

jimf

traume wrote: »

Please see attached.

that's not a gauge that's an air damper for the burner

also just to add to your woes the hose on the oil supply to your burner should not be outside the cabin they are not weather proof

John.G

You may find that the make up water is from that storage tank, I would get that poppet NRV removed and install a swing check valve on (or make) a short horizontal length of pipework, ensure the expansion vessel pre pressure is only ~ 0.3/0.5 bar and try that.
My neighbour had/has a boiler very like that (can't remember the model just now but will find it) he did have a separate F&E tank but when when the boiler was installed it was converted to (semi) sealed with one of those poppet NR valves, it used to occasionally cut out on its thermostat (not trip) after a few minutes from cold, I replaced the poppet valve with a swing check and he had no more problems although he never had any air problems, the poppet valve was gunged up as well which of course didn't help matters.

Boiler is a Warmflow B90HE.

traume

John.G wrote: »

You may find that the make up water is from that storage tank, I would get that poppet NRV removed and install a swing check valve on (or make) a short horizontal length of pipework, ensure the expansion vessel pre pressure is only ~ 0.3/0.5 bar and try that.
My neighbour had/has a boiler very like that (can't remember the model just now but will find it) he did have a separate F&E tank but when when the boiler was installed it was converted to (semi) sealed with one of those poppet NR valves, it used to occasionally cut out on its thermostat (not trip) after a few minutes from cold, I replaced the poppet valve with a swing check and he had no more problems although he never had any air problems, the poppet valve was gunged up as well which of course didn't help matters.

Changing the valve actually makes a lot of sense. If the valve has got some debris inside it could start to seize up and not let enough water in.
Do I understand it right- Swing check valve works on flow, but poppet nrv works by gravity pushing the water down? So if the pressure from the tank is not enough, then there would be lack of water in the system as it is condensing boiler and uses some amount of water on every run?!

John.G

They both require a differential pressure to open, the swing check, negible, can't remember a poppet valve differential presure requirement but yes as depending on where its installed it may not open virtually a tall, your tank head pressure is ~ 0.3/0.5 bar (3/5M), remember the swing check must be installed on the horizontal.

Any boiler should not consume any water on any/every run.

traume

John.G wrote: »

They both require a differential pressure to open, the swing check, negible, can't remember a poppet valve differential presure requirement but yes as depending on where its installed it may not open virtually a tall, your tank head pressure is ~ 0.3/0.5 bar (3/5M), remember the swing check must be installed on the horizontal.

At first I will try to change the poppet nrv. Then have to wait for few cooler days to test it out.
Thanks, at least in my head it makes perfect sense.

John.G

That Poppet valve looks a bit strange, check the arrow direction on it!.

Paullimerick

Why do people use spring or flap nrv off a tank in the attic. As any plumber worth his salt knows its so wrong. If it ever leaked back up through expansion. Change that to a auto fill valve. Blank pipe at the tank and connect other side to the mains. It sounds like to me a faulty pump.

traume

John.G wrote: »

That Poppet valve looks a bit strange, check the arrow direction on it!.

It is pointing downward.

John.G

Paullimerick wrote: »

Why do people use spring or flap nrv off a tank in the attic. As any plumber worth his salt knows its so wrong. If it ever leaked back up through expansion. Change that to a auto fill valve. Blank pipe at the tank and connect other side to the mains. It sounds like to me a faulty pump.

Could be pump even though apparently no problems on hot water.

Agree that make up should not be fed from CWST, lots of houses around me converted to gas fired boilers when gas became available and most were converted by bord gais approved personnel, in most cases they converted to semi sealed systems but all these houses had/have F&E tanks + combined vent&cold feed when built in 1970/72, I can only assume that the reason for not going the "proper" route was because a semi sealed system will run with the lowest possible pressures or maybe it was just pure laziness?.

traume

Paullimerick wrote: »

Why do people use spring or flap nrv off a tank in the attic. As any plumber worth his salt knows its so wrong. If it ever leaked back up through expansion. Change that to a auto fill valve. Blank pipe at the tank and connect other side to the mains. It sounds like to me a faulty pump.

Sorry, I'm not sure I understand, is the pressure in the system/expansion vessel lower then the pressure from the attic?
For what ever reason I was under impression that pressure is quite high.

John.G

Because (if) the make up is fed from a tank with water which may be potable then when the boiler heats up, the NRV closes and the expansion is taken up by the expansion vessel but if the NRV is leaking then danger of tank pollution from boiler/system contents including inhibitor.

traume

John.G wrote: »

Because (if) the make up is fed from a tank with water which may be potable then when the boiler heats up, the NRV closes and the expansion is taken up by the expansion vessel but if the NRV is leaking then danger of tank pollution from boiler/system contents including inhibitor.

This makes sense, but if it is connected to mains, can't it leak back? Is the pressure in the mains larger than pressure in the heating system?

traume

John.G wrote: »

Could be pump even though apparently no problems on hot water.

Agree that make up should not be fed from CWST, lots of houses around me converted to gas fired boilers when gas became available and most were converted by bord gais approved personnel, in most cases they converted to semi sealed systems but all these houses had/have F&E tanks + combined vent&cold feed when built in 1970/72, I can only assume that the reason for not going the "proper" route was because a semi sealed system will run with the lowest possible pressures or maybe it was just pure laziness?.

Is there a way to test the waterpump or it has to be changed to test?

Would it mean that waterpump sucks in the air and then airlocks?

John.G

It could be the pump even though the system is OK on hot water only and you did say it ran from June 2019 to Feb 2020.
You have to start somewhere to resolve the issue and if you can't easily get a plumber in then maybe do the simple/easy things first.

Dtp1979

Op, those Warmflow boilers have a few auto air vents on the pipes behind the pump. Make sure they’re all closed. It could be a simple thing like one of them sucking in air when the pump starts up.

traume

Dtp1979 wrote: »

Op, those Warmflow boilers have a few auto air vents on the pipes behind the pump. Make sure they’re all closed. It could be a simple thing like one of them sucking in air when the pump starts up.

Not sure what exactly am I looking at, but will lift off the top lid tomorrow and check.

traume

John.G wrote: »

It could be the pump even though the system is OK on hot water only and you did say it ran from June 2019 to Feb 2020.
You have to start somewhere to resolve the issue and if you can't easily get a plumber in then maybe do the simple/easy things first.

Thanks John, looks like I have to change the mindset on this. If changing nrv wont change anything, it well could be next step.

Could faulty expansion vessel contribute to the issue?

John.G

traume wrote: »

Not sure what exactly am I looking at, but will lift off the top lid tomorrow and check.

Air Vents.

John.G

traume wrote: »

Thanks John, looks like I have to change the mindset on this. If changing nrv wont change anything, it well could be next step.

Could faulty expansion vessel contribute to the issue?

A faulty E.vessel will usually exhibit itself by lifting the PRV (safety) valve on the boiler every time it heats up as the E.vessel could be full of water due to a ruptured diaphragm or it may have lost all its air pressure. Remove the plastic cover on the top of the E.vessel and press the schrader valve stem with your fingernail, if water comes out it has failed, if no pressure then it has lost its pre charge pressure but both cases should result in the PRV lifting. Also if the pre charge pressure is too high ~ 2 bar then this can also result in the PRV lifting.

John.G

You really only should consider the above (NRV) as a short term fix until you can get a proper mains filling loop installed, if you are handy yourself then all you need is a filling loop, a few compression fittings and a pressure gauge located near the filling loop so as that you can see what you are doing, you do not need one of these horrible auto filling devices (simply a pressure reducing valve). You can install the filling loop anywhere convenient, if you do decide to go this route just let us know where you are installing it as its elevation with respect to the E.vessel has to taken in to account and is very important for calculating the fill pressure.

traume

John.G wrote: »

You really only should consider the above (NRV) as a short term fix until you can get a proper mains filling loop installed, if you are handy yourself then all you need is a filling loop, a few compression fittings and a pressure gauge located near the filling loop so as that you can see what you are doing, you do not need one of these horrible auto filling devices (simply a pressure reducing valve). You can install the filling loop anywhere convenient, if you do decide to go this route just let us know where you are installing it as its elevation with respect to the E.vessel has to taken in to account and is very important for calculating the fill pressure.

Very usefull info here! Thanks!

Today I opened up the boiler and found that there are 2 automatic bleeding vents.
The lower one had a good bit of air in and it had a bit of deposits around it. Looks like it has been doing its job. The top one had only very small amount of air in.

Should screws be tightened or they should be opened?

Is there any chance that pipes are connected wrong? Intake-out.

Dtp1979

I personally always leave them closed.

Wearb

Dtp1979 wrote: »

I personally always leave them closed.

I leave them closed also and open them at service time. Give an indication of state of system if little air after a year.

John.G

traume wrote: »

Very usefull info here! Thanks!

Today I opened up the boiler and found that there are 2 automatic bleeding vents.
The lower one had a good bit of air in and it had a bit of deposits around it. Looks like it has been doing its job. The top one had only very small amount of air in.

Should screws be tightened or they should be opened?

Is there any chance that pipes are connected wrong? Intake-out.

Re pipes incorrectly connected. Assuming that the one labelled "CH Return" is the return just fire up the boiler for a few minutes and that should be the cooler of the two.

I presume the auto air vents were shut off?, most seem to prefer them shut off as stated above and opened occasionally.

Also check that the magnetic filter is installed in the return and is not connected between the flow and return.

traume

John.G wrote: »

Re pipes incorrectly connected. Assuming that the one labelled "CH Return" is the return just fire up the boiler for a few minutes and that should be the cooler of the two.

I presume the auto air vents were shut off?, most seem to prefer them shut off as stated above and opened occasionally.

Also check that the magnetic filter is installed in the return and is not connected between the flow and return.

Vents were closed.
Will check tomorrow morning.

rightjob!

OP is the safety valve off the boiler ever dripping?
Is the expansion vessel full of water?
Any pressure gauges on the system?
Do you have a back boiler connected to the heating?
Is it definitely semi sealed?
You will know if that Nrv is letting water pass back through up to the tank if when the heating is on the feed side of the pipe will be roasting.
Doubt it is passing as these usually get stuck in a closed position.

John.G

traume wrote: »

1 cold water tank in the attic.
No pressure gauges present for the heating system, the only gauge is on the burner and it is at 3 bar mark all the time.
Expansion vessel is fitted. Not sure how to check if it is functioning.

Just looking at that NRV again in that 3/4" or 1" pipe, normally 1/2" piping is used as the make up so have a good look around the airing cupboard/hot water cylinder as there may be another (1/2") NRV there somewhere or however unlikely something like shown in post #33.

traume

Pipe above NRV never gets hot. It is about 1m above the main loop where it enters.

John.G

traume wrote: »

Pipe above NRV never gets hot. It is about 1m above the main loop where it enters.

If the main loop you are referring to is the central heating loop then that is the filling supply alright.

The reason I mentioned it is that I have seen 3/4" pipes like that (with a NRV) supplying a shower pump.

rightjob!

traume wrote: »

Pipe above NRV never gets hot. It is about 1m above the main loop where it enters.

Grand so the nrv isnt passing.
Is that feed connected to a mains or a tank?

traume

Hi all, thanks so much for help! In 2-3 weeks I will change tank fed system to feed from mains. Yous are very convincing!
Will change expansion tank as well.

Question, how can I calculate what pressure can my heating system handle once I change to mains feed?

Dtp1979

traume wrote: »

Hi all, thanks so much for help! In 2-3 weeks I will change tank fed system to feed from mains. Yous are very convincing!
Will change expansion tank as well.

Question, how can I calculate what pressure can my heating system handle once I change to mains feed?

1.5 bar.
Did closing the vents work?

traume

It is hard to say as now we are not heating the house, only the the hot water, and it never fails while only heating the water.

John.G

With any sealed (or semi sealed) system then as the E,vessel can fail and be filled with water, the pressure will rise to and lift the boiler safety valve at 3 bar so your system pipework/rads etc should be able to deal with this without any leakage.

The normal pressure will be lower than this depending on the system volume and temperature, the E.vessel volume and its pre charge and filling pressures but if one assumed a system volume of 80 litres, a E.vessel pre charge pressure of 1 bar, a filling pressure of 1.5 bar then one might expect a final pressure with a fully heated system of 2.33/2.13/2.0 bar (max) for E.vessel volumes of 8/10/12 litres so the bigger the E.vessel the less the pressure rise, you cannot oversize a E.vessel.

You say you are now only heating the hot water.... so have you made changes to your system? and if so what exactly?.

Edit: I see you are planning to change to a sealed system in a few weeks time.

John.G

traume wrote: »

It is hard to say as now we are not heating the house, only the the hot water, and it never fails while only heating the water.

You normally keep the vent closed anyway?. IMO, the shouldn't draw in air with a sealed system but might dribble a bit when pressurised.

traume

John.G wrote: »

You normally keep the vent closed anyway?. IMO, the shouldn't draw in air with a sealed system but might dribble a bit when pressurised.

Air valves on the boiler are always closed, valve for the feed is always opened (If thats what you mean).

traume

John.G wrote: »

With any sealed (or semi sealed) system then as the E,vessel can fail and be filled with water, the pressure will rise to and lift the boiler safety valve at 3 bar so your system pipework/rads etc should be able to deal with this without any leakage.

The normal pressure will be lower than this depending on the system volume and temperature, the E.vessel volume and its pre charge and filling pressures but if one assumed a system volume of 80 litres, a E.vessel pre charge pressure of 1 bar, a filling pressure of 1.5 bar then one might expect a final pressure with a fully heated system of 2.33/2.13/2.0 bar (max) for E.vessel volumes of 8/10/12 litres so the bigger the E.vessel the less the pressure rise, you cannot oversize a E.vessel.

You say you are now only heating the hot water.... so have you made changes to your system? and if so what exactly?.

Edit: I see you are planning to change to a sealed system in a few weeks time.

Yes, you and other board members have convincent me to move to the Sealed system. I have a friend who is enthusiast plumber will help me out on this.
The plan is to connect the feed to the mains pipe in the attic, add additional valve on the mains, remove current NRV and instead put in valve and pressure gauge and then change the E.Vessel.

I have not done any changes now as at the minute I won't see the problem until I start heating all 3 zones.

We don't have immersion heater, so the only way for us to heat the water is boiler and and as I wrote before - we never had air pulled if only using the hot water zone.

At the very start I though that issue is because automatic air vent is failing, but I installed new Automatic Air vent in the hot press and then installed one on the towel radiator as well. What bugs me is - why air is gathering only at the circulation pump.

If all of the above changes won't help (will know only in autumn) will change the circulation pump.

On different issue, when bleeding radiators, water is nearly black and smells like an oil. Looks like i have to think about flushing the system as well.

John.G

Re air gathering at Circ pump, have a look and see where the E.vessel is connected into the system, see if its into the return or the flow. Ideally the E.vessel should be located as close to the circ pump as possible and connected into the suction side of the pump, this ensures that the pump suction is always at the E.vessel pressure, the pump discharge will then run at the pump head+the E.vessel pressure, if connected into the flow side of the pump then the pump suction will run at the E.vessel pressure - the pump pressure (which can lead to air ingress due to low/negative pressures) and the pump discharge at the E.vessel pressure, however with a fully sealed system with relatively high pressures then this isn't as important but in your case (at the moment) with pressures/heads of only 0.4/0.6 bar when cold then of far more importance.

I would also remove the circ pump and then remove the head, you can then clean out the ports and the impeller which more than likely will have some build up, even if no build up ensure that you rejoint the pump connections with rubber gaskets as the fibre type can draw in air at the pump suction even though may it not display any signs of leakage.

Re system flushing, you can get this professionally done but can also just flush out each rad with a hose and likewise the pipework, I helped a neighbour do this recently and even though time consuming worked fine in his case, your friend will advise on this anyway.