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Air pulled in the Heating system / life lesson

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    #32
    John.G
    Registered Users Posts: 3,474 ✭✭✭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.


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    #33
    John.G
    Registered Users Posts: 3,474 ✭✭✭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.


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    #34
    traume
    Registered Users Posts: 124 ✭✭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.


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    #35
    Dtp1979
    Registered Users Posts: 12,736 ✭✭✭✭Dtp1979


    I personally always leave them closed.


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    #36
    Wearb
    Moderators, Home & Garden Moderators Posts: 6,231 Mod ✭✭✭✭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.

    Please follow site and charter rules. "Resistance is futile"



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    #37
    John.G
    Registered Users Posts: 3,474 ✭✭✭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.


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    #38
    traume
    Registered Users Posts: 124 ✭✭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.


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    #39
    rightjob!
    Registered Users Posts: 478 ✭✭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.


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    #40
    John.G
    Registered Users Posts: 3,474 ✭✭✭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.


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    #41
    traume
    Registered Users Posts: 124 ✭✭traume


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


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    #42
    John.G
    Registered Users Posts: 3,474 ✭✭✭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.


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    #43
    rightjob!
    Registered Users Posts: 478 ✭✭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?


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    #44
    traume
    Registered Users Posts: 124 ✭✭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?


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    #45
    Dtp1979
    Registered Users Posts: 12,736 ✭✭✭✭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?


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    #46
    traume
    Registered Users Posts: 124 ✭✭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.


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    #47
    John.G
    Registered Users Posts: 3,474 ✭✭✭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.


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    #48
    John.G
    Registered Users Posts: 3,474 ✭✭✭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.


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    #49
    traume
    Registered Users Posts: 124 ✭✭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).


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    #50
    traume
    Registered Users Posts: 124 ✭✭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.


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    #51
    John.G
    Registered Users Posts: 3,474 ✭✭✭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.


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    #52
    traume
    Registered Users Posts: 124 ✭✭traume


    Today I opened up the MagnaClean, I didn't expect to see so much sludge. I have to consider Power Flush. See in attachment. I doubt I hewting system cleaner will help here as if there is so much sludge on the filter and if bleeding radiators black and smelly water comes out: either i remove the radiators or get powerflush.

    I checked where E.Vessel is connected and it is connected to the feeder pipe approximately 1.2m below NRV. Then I can see that radiator return pipes connects to the same pipe and then goes down in the floor. It is not clear in the images, but added them anyway.

    E.Vessel has the air in it. I don't know what pressure is in, but it is definately there.

    What is strange - after disconnected the Magna Clean I let in the system approximately half litre of air and it is right before the Circulation Pump, but it started right up without a hickup and without airlocking. I let it run for a few minutes and opened up the bleeding screw on the circulation pump - no air.

    Looks like for now, I can't do much more then convert to sealed system and then powerflush.


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    #53
    John.G
    Registered Users Posts: 3,474 ✭✭✭John.G


    Maybe the magnetic filter was impeding the flow into the pump suction and cleaning it helped, there certainly seems a good build up, wonder how much it has removed from the rads (wall thickness etc) and will the increased system pressure show up any weaknesses as indeed the power flush may too.

    The E.vessel connection point is on the return at any rate.

    Should also have asked where the pump is installed (boiler flow or return) and its make/model and present setting. I can see the pump from the photo but not the setting.


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    #54
    rightjob!
    Registered Users Posts: 478 ✭✭rightjob!


    I wouldn’t convert it to a fully sealed system,its not going to do much for you.(if you already have a semi sealed)

    If you have air coming in its either
    -a leak
    - air getting sucked in at vents or if you have an open vent system.
    -the expansion vessell is burst and causing the safety valve to open and let water out.

    That system definitely needs a power flush from looking at the photo of the magnaclean.
    If you are going down the route of getting a powerflush, they will more than likely stick a filling loop on it for you.


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    #55
    John.G
    Registered Users Posts: 3,474 ✭✭✭John.G


    Fully sealed systems tend to be set up with minimum pre charge/filling pressures of 1/1.5 bar so the lowest system pressure will generally be ~ 1.5 bar so the system will generally be 1.5 bar with a minimum of 1.0 bar when cold whereas semi sealed results in a pressure of ~ 0.4 bar (static head) every time the system cools down so on start up will tend to pull in air somewhere if any restrictions or whatever in the system, I know of one system which was converted to semi sealed because of ongoing (air ingress) problems with a vented system and even though it improved the situation, it didn't cure it but changing to fully sealed did. Semi sealed will work in the majority of cases though and is far more forgiving on very old systems due to the lower pressures involved.


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    #56
    traume
    Registered Users Posts: 124 ✭✭traume


    Update:
    Yesterday converted to Fully sealed. Pressure is dropping very rapidly, approximately 0.2-0.4 bars every hour.
    No visible leaks. I didn't have pressure guge previously and could not judge the pressure, now I can.

    So what I have done now is - I added a valve on the return so now I can isolate the system (motorized valves for each zone). It is needed to find out if the leak in the house or it is Hotpress-Boiler run. Waiting and hoping that pressure will drop now so I know that those are the pipes which are accesible.
    They can't be leaking from hotpress to outer wall as I went through every inch and could not find a drop of water. So either Exterior Wall to Boiler or somewhere in the house.

    Is it worth trying Fernox Leak sealer? At the minute 2bars are lost in couple of hours, I would imagine it should be quite large leak. I read a lot of similar cases fixed with Fernox Leak sealer but I'm afraid I will clog the pump or heat exchanger?!

    Else, Return and feed pipes on the boiler are mixed up...After starting the boiler first pipe to heat up in the Hotpress is the return pipe (the one where Water is topped up and no motorized valves), so I have to get this sorted as well. If i understand from you guys right - It can't be the cause for the leak anyway, but it explains why air was pushed in the feed pipe instead of radiators.

    Thanks everyone for good ideas!


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    #57
    John.G
    Registered Users Posts: 3,474 ✭✭✭John.G


    A few queries;

    Where is the pressure gauge located? (eg ground floor etc)
    Where is the EV located?
    What is the capacity of the EV.
    What was the EV pre charge pressure?
    What was/is the EV filling pressure? (cold)

    Regarding "Return and feed pipes on the boiler are mixed up", if they were then the boiler stat would be measuring the return temp and the actual flow temp would have been anything from 10C to 25C higher, wonder what effect the reversed flow has on a condensing boiler re corrosion.
    I would check at the boiler that the flow&return are actually reversed.

    Also check no water coming from condenate trap drain when boiler is cold, you may have to disconnect the drain somewhere to observe this, watch it for good few minutes because some of these traps discharge the water in bursts of 1/2 a litre or so at the time and are not continuous.


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    #58
    Dtp1979
    Registered Users Posts: 12,736 ✭✭✭✭Dtp1979


    Chances are the coil is gone on your hot am water cylinder. Blank off the coil and pressurise the system. You won’t be long finding out if that’s the culprit.


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    #59
    Paullimerick
    Registered Users Posts: 200 ✭✭Paullimerick


    It may be the coil. But i doubt it as ive not heard the op on about his overflow dripping in the morning. The flow and return mixed uo going onto the cylinder is nothing lets be honest to worry about. Might have to change the MV direction. Time for a compressor my thinks.


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    #60
    jimf
    Registered Users Posts: 3,952 ✭✭✭jimf


    im no plumber but was wondering if the coil in cyl was gone would running off the water in a bath etc show water discolouration

    as the domestic and heating water are mixing and that's the only place they can potentially meet

    but as paul says above no suggestion of overflow dripping


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    #61
    traume
    Registered Users Posts: 124 ✭✭traume


    John.G wrote: »
    A few queries;

    Where is the pressure gauge located? (eg ground floor etc)
    Where is the EV located?
    What is the capacity of the EV.
    What was the EV pre charge pressure?
    What was/is the EV filling pressure? (cold)

    Regarding "Return and feed pipes on the boiler are mixed up", if they were then the boiler stat would be measuring the return temp and the actual flow temp would have been anything from 10C to 25C higher, wonder what effect the reversed flow has on a condensing boiler re corrosion.
    I would check at the boiler that the flow&return are actually reversed.

    Also check no water coming from condenate trap drain when boiler is cold, you may have to disconnect the drain somewhere to observe this, watch it for good few minutes because some of these traps discharge the water in bursts of 1/2 a litre or so at the time and are not continuous.

    Feed pipe comes from the attic, then down in the 1st floor in the hotpress I have Valve and after the valve pressure gauge. Under the valve there is a splitter where one pipe goes to the E.Vessel, return from radiators and then pipe goes straight in the floor and back to the boiler.

    I'm not sure what EV is, if you mean total system then I know that I have 11 radiators.

    Pressure does not change cold/hot. It is the same all the time but drops only if cold. I previously left boiler running for 3 hours and pressure stayed the same, once system cooled down pressure started to drop until 0 bars.

    Last night I pressurized the system to 1.5bar.

    I have not seen any water coming out of the condensate pipe on the boiler.


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