Air in towel radiator

[Sammy1]

Our upstairs towel radiator keeps filling with air at the top. We had a new system boiler, new tank and new pipework fitted in October. The new tank is in the garage which is underneath the house and the new boiler is in the kitchen at ground floor level. We also had underfloor heating installed in our kitchen, the manifold is in the garage under the house. The 3 towel radiators come on when either the hot water is on or the underfloor heating is on, but not when the other radiators are on. We keep needing to let air out of the upstairs towel radiator and top the boiler up with water at the same time. The pipes in the walls and under the floors are no longer easily accessible. Where is the air coming from and how do we fix it? Please help!

 

[Jerry]

I take it you are not getting any drop in pressure between bleeding the towel rad?

I have heard of pumps being able to suck air into a heating system. Maybe some other old hands can comment? I believe its usually via the TRV's

I doubt a leak sealer would help and its probably not a good idea to turn the pump speed down.

A dirty fix might me to install a mini auto air vent on the rad. I have seen these the same size/shape as a regular radiator vemt.

 

[Sammy1]

I take it you are not getting any drop in pressure between bleeding the towel rad?

I have heard of pumps being able to suck air into a heating system. Maybe some other old hands can comment? I believe its usually via the TRV's

I doubt a leak sealer would help and its probably not a good idea to turn the pump speed down.

A dirty fix might me to install a mini auto air vent on the rad. I have seen these the same size/shape as a regular radiator vemt.

Hi Jerry, thank you. We bled them again at the weekend but instead of bleeding them first we tried turning the water feed to the boiler on first and the pressure dial did go up when we did this (it was still above the minimum before opening the tap on the water feed). Does this mean air is getting in via the pump?

 

[king of pipes]

Alladin auto air vents in the towel rails will expel any air , is there enough expansion for the heating ? the expansion vessel in the system boiler is only enough for 6 -8 medium size rads you may well need a extra one fitted if you have more than this ? a good quality system inhibitor is needed to protect against corrosion within the system which itself can cause symptoms similar to build up of air when in reality its not . Kop

 

[SJB060685]

Was any plastic pipe used on the new installation?

 

[Sammy1]

Alladin auto air vents in the towel rails will expel any air , is there enough expansion for the heating ? the expansion vessel in the system boiler is only enough for 6 -8 medium size rads you may well need a extra one fitted if you have more than this ? a good quality system inhibitor is needed to protect against corrosion within the system which itself can cause symptoms similar to build up of air when in reality its not . Kop

Alladin auto air vents in the towel rails will expel any air , is there enough expansion for the heating ? the expansion vessel in the system boiler is only enough for 6 -8 medium size rads you may well need a extra one fitted if you have more than this ? a good quality system inhibitor is needed to protect against corrosion within the system which itself can cause symptoms similar to build up of air when in reality its not . Kop

Thank you Kop. No, we don’t have an extra one. The boiler runs the underfloor heating, 10 radiators (some rooms have more than one rad in) and 3 towel rails. All the pipes are new apart from the pipes to the radiators. We don’t seem to have air in the radiators that we’ve noticed, just the towel rails. The plumber said he put inhibitor in so hope that side of things is ok.

 

[Sammy1]

Thank you Kop. No, we don’t have an extra one. The boiler runs the underfloor heating, 10 radiators (some rooms have more than one rad in) and 3 towel rails. All the pipes are new apart from the pipes to the radiators. We don’t seem to have air in the radiators that we’ve noticed, just the towel rails. The plumber said he put inhibitor in so hope that side of things is ok.

Does the towel rail system need to be drained in order to fit the auto air vents?

 

[Sammy1]

Was any plastic pipe used on the new installation?

Yes, plastic pipe was used in an internal wall but the majority is copper.

 

[king of pipes]

You need another expansion vessel for a start, then fit the vents they are easy to do isolate your valves open the air vent on the towel rail make sure you have something to soak up the water should it be pressurised up, I like to leave the manual air vent in and put the alladin one where it's blanked off once complete it's a matter of turning back on . Kop

 

[Sammy1]

No I’m

You need another expansion vessel for a start, then fit the vents they are easy to do isolate your valves open the air vent on the towel rail make sure you have something to soak up the water should it be pressurised up, I like to leave the manual air vent in and put the alladin one where it's blanked off once complete it's a matter of turning back on . Kop

Thank you

 

[Sammy1]

No I’m

Thank you

We have a large-ish white round tank on the garage wall next to the hot water tank and underfloor heating manifold - I thought it was just for the underfloor heating but could this be the extra expansion vessel for the system?

 

[king of pipes]

Can you post a picture of it please , i would say thats the expansion vessel for the unvented cylinder they are usually white or blue? the heating ones are normally red or grey ? it should look like below

 

[Sammy1]

Can you post a picture of it please , i would say thats the expansion vessel for the unvented cylinder they are usually white or blue? the heating ones are normally red or grey ? it should look like below

Can you post a picture of it please , i would say thats the expansion vessel for the unvented cylinder they are usually white or blue? the heating ones are normally red or grey ? it should look like below

Thanks for your help. It’s white…here’s photos of all the new stuff installed…

 

[king of pipes]

As I thought thats for the unvented cylinder it says on the label for sanitary application you need a 10 litre one fitting in the return pipework back to the boiler it should be lagged up aswell

 

[Sammy1]

As I thought thats for the unvented cylinder it says on the label for sanitary application you need a 10 litre one fitting in the return pipework back to the boiler it should be lagged up aswell

Ok thanks, we need a 10l expansion vessel? What should be lagged, the expansion vessel itself or the pipework or both? Although the tank etc is in the garage, it is an internal garage and is surprisingly warm.

 

[SJB060685]

The pipe work needs lagging. Any idea of system volume? A 10 litre is probably more than enough but it wouldn’t hurt to run some quick maths.

 

[Sammy1]

The pipe work needs lagging. Any idea of system volume? A 10 litre is probably more than enough but it wouldn’t hurt to run some quick maths.

Thanks, sorry, not sure how I’d work that out..,

 

[ShaunCorbs]

How many radiators do you have and any big ones eg over 1.4m

 

[SJB060685]

Unless you have a pretty accurate idea of the pipe sized and length of runs in the system you would just be guessing. This is something your installer should have been aware of and considered at design stage. 10 litres is probably enough, King Of Pipes knows his stuff so I’m not going to argue with him but I’d hate for a 20 to go in and then discover you needed a bit more.

 

[Sammy1]

How many radiators do you have and any big ones eg over 1.4m

 

[Sammy1]

10 radiators (5 are over 1.4m), 3 towel rails (& underfloor heating in one room). Potential loft conversion in the future which would be 2-3 extra radiators & 1 extra towel rail. So the extra expansion vessel should stop air getting in completely?

 

[ShaunCorbs]

18l should be fine the standard vessel eg inside the boiler is 10l

 

[SJB060685]

Sorry I haven’t read all previous comments. The additional vessel is needed to help accumulate the expanding water.

 

[Sammy1]

18l should be fine the standard vessel eg inside the boiler is 10l

Ok thanks

 

[Sammy1]

Sorry I haven’t read all previous comments. The additional vessel is needed to help accumulate the expanding water.

Ok thank you, I wonder why the plumber didn’t fit one

 

[SJB060685]

It’s something they should of been aware of. All system/combi boilers only come with a reasonably small vessel. Quite often the system volume is too much for a standard fitted vessel. A few factors help arrive at a suitable size. System volume, operating temperatures, min and max running pressure. The maths enables you to arrive at an accurate answer for that current system but there is no such thing as too large a vessel, the only problem is additional cost for larger than needed vessels and siting them.
As for the air problem. You did reply to my previous comment about plastic pipe. I would like to think it’s barrier pipe that’s been used?

 

[Sammy1]

It’s something they should of been aware of. All system/combi boilers only come with a reasonably small vessel. Quite often the system volume is too much for a standard fitted vessel. A few factors help arrive at a suitable size. System volume, operating temperatures, min and max running pressure. The maths enables you to arrive at an accurate answer for that current system but there is no such thing as too large a vessel, the only problem is additional cost for larger than needed vessels and siting them.
As for the air problem. You did reply to my previous comment about plastic pipe. I would like to think it’s barrier pipe that’s been used?

 

[Sammy1]

Ok thanks, could the lack of a second vessel be causing the air intake? I have a photo of the plastic pipes..the horizontal sections lead to a towel rail on the other side of the wall, the rest of the pipework outside of this photo is copper.

 

[Sammy1]

Ok thanks, could the lack of a second vessel be causing the air intake? I have a photo of the plastic pipes..the horizontal sections lead to a towel rail on the other side of the wall, the rest of the pipework outside of this photo is copper.

Better quality photo…

 

[SJB060685]

No the lack of an additional vessel is not going to be the cause of air ingress. A poorly positioned pump in relation to vessel location can cause frequent venting of radiators but that’s a pressure problem and not air ingress.
I honestly can’t identify that plastic pipe.

 

[Sammy1]

No the lack of an additional vessel is not going to be the cause of air ingress. A poorly positioned pump in relation to vessel location can cause frequent venting of radiators but that’s a pressure problem and not air ingress.
I honestly can’t identify that plastic pipe.

Ok thanks. I’m assuming the pump is in our garage with the tank?….the boiler is up one floor & approx 9m away horizontally.

 

[SJB060685]

I’d imagine the pump is internal of the boiler and located correctly with respect to the vessel

 

[king of pipes]

Overall your installation seems ok it's easy to criticize and we all have our working practices , I personally don't think the use of plastic pipe is a cause of air ingress it looks like speed fit pipe and fittings that have been used which are reliable and have been used widely for years , any pipework around the cylinder hot or cold should be insulated as should any pipework in cold areas and voids , your heating pump will be inside your boiler casing the property seems like a large family home and a system boiler with a internal pump wouldn't of been my choice as these boilers struggle to move the volume of water in the system and absorb the expansion there are ways to improve this and I can see why maybe it was fitted because there is not much space , has the system always been problematic ? is the work completed ? we could advise ways to improve your system but it's really the installers responsibility to make sure its commissioned and working correctly you plan to extend your home further and this without doubt will cause more problems unless improvements are made . Regards kop

 

[Sammy1]

Overall your installation seems ok it's easy to criticize and we all have our working practices , I personally don't think the use of plastic pipe is a cause of air ingress it looks like speed fit pipe and fittings that have been used which are reliable and have been used widely for years , any pipework around the cylinder hot or cold should be insulated as should any pipework in cold areas and voids , your heating pump will be inside your boiler casing the property seems like a large family home and a system boiler with a internal pump wouldn't of been my choice as these boilers struggle to move the volume of water in the system and absorb the expansion there are ways to improve this and I can see why maybe it was fitted because there is not much space , has the system always been problematic ? is the work completed ? we could advise ways to improve your system but it's really the installers responsibility to make sure its commissioned and working correctly you plan to extend your home further and this without doubt will cause more problems unless improvements are made . Regards kop

 

[Sammy1]

Thanks kop. Which boiler should we have had? Prior to this we had a standard boiler & hot water tank (not pressurised system) & had no problems. We went for system as we were told it was better for 2+ bathrooms (we have 2 bathrooms at the moment). We were told our old boiler probably couldn’t handle the underfloor heating. So if we get another expansion vessel fitted is this enough? We can lag the visible pipework ourselves, under the floors is a bit tricky now. Is there anything else that needs changing? Is the likely cause of the air ingress a leak or is there anything else we could do to try to stop the air getting in?

 

[Sammy1]

Thanks kop. Which boiler should we have had? Prior to this we had a standard boiler & hot water tank (not pressurised system) & had no problems. We went for system as we were told it was better for 2+ bathrooms (we have 2 bathrooms at the moment). We were told our old boiler probably couldn’t handle the underfloor heating. So if we get another expansion vessel fitted is this enough? We can lag the visible pipework ourselves, under the floors is a bit tricky now. Is there anything else that needs changing? Is the likely cause of the air ingress a leak or is there anything else we could do to try to stop the air getting in?

Yes, the work is completed & there’s space in the garage for another expansion vessel. The water tank was originally upstairs in the airing cupboard, now moved to the internal garage to allow stairs to be built to the loft. The boiler before & now is in a kitchen cupboard (no top & bottom to the cupboard).

 

[king of pipes]

What you have been told is correct a sealed system boiler and unvented cylinder is the best choice for your property you're boiler is not necessarily wrong it's not unusual to use a system boiler but it needs piping a different way , you will need a extra expansion vessel to accommodate the volume of heated water in the system, the insulation needs doing just do what is visible and easy to access I would get this completed first fit the aav's, future improvements can be made if necessary.

 

[John.g]

There seems to be 2 x red exp. vessels and 1 x white, one red is adjacent to the boiler?, what volume is this.
You can tell easily if the installed exp. volume is sufficient by turning on all heating systems and noting the boiler pressure when all systems hot, if not > 2.5bar then OK from a expansion point of view but maybe other reasons for installing extra one?.
Can you also post a close up photo of the UPM pump, when its running, don't know if its running on one of its manual modes or is PWM controlled.

 

[Sammy1]

What you have been told is correct a sealed system boiler and unvented cylinder is the best choice for your property you're boiler is not necessarily wrong it's not unusual to use a system boiler but it needs piping a different way , you will need a extra expansion vessel to accommodate the volume of heated water in the system, the insulation needs doing just do what is visible and easy to access I would get this completed first fit the aav's, future improvements can be made if necessary.

Thank you. What other improvements would you recommend? And how to we fix this annoying air ingress?

 

[king of pipes]

I'll go into it later I'm now got to work regards kop

 

[king of pipes]

There seems to be 2 x red exp. vessels and 1 x white, one red is adjacent to the boiler?, what volume is this.
You can tell easily if the installed exp. volume is sufficient by turning on all heating systems and noting the boiler pressure when all systems hot, if not > 2.5bar then OK from a expansion point of view but maybe other reasons for installing extra one?.
Can you also post a close up photo of the UPM pump, don't know if its running on one of its manual modes or is PWM controlled.

???

 

[Sammy1]

???

???

There seems to be 2 x red exp. vessels and 1 x white, one red is adjacent to the boiler?, what volume is this.
You can tell easily if the installed exp. volume is sufficient by turning on all heating systems and noting the boiler pressure when all systems hot, if not > 2.5bar then OK from a expansion point of view but maybe other reasons for installing extra one?.
Can you also post a close up photo of the UPM pump, when its running, don't know if its running on one of its manual modes or is PWM controlled.

The photos of the red ones are not my house. Pressure does not go over 2.5. What is the UPM pump? The black box near the water tank?

 

[Sammy1]

I'll go into it later I'm now got to work regards kop

Thank you

 

[John.g]

The photos of the red ones are not my house. Pressure does not go over 2.5. What is the UPM pump? The black box near the water tank?

Apoligies, the red ones are atypical as shown by KOP.

2.5bar is OK for the moment as long as you don't install any more rads etc.
Re Air venting, when you vent the air, then theoretically, if you don't top up the system, if air is entering the system the pressure should build up again, if it doesn't then perhaps air still in the UFH loops even though this might be unlikely since last October, anyway, after the next venting do not top up except that the pressure is excessively low and see what happens.

The Pump is on the UFH manifold as shown, you might post a close up photo of it when running to show the LEDs.
Also if you can see the UFH manifold, the flow rates for each loop and the manifold flow and return temperatures, if available.

 

[king of pipes]

Thank you

One other thing to try is tie wrap a plastic bag on the end of the safety valve of the boiler for 24 hrs run the system heat the water and just monitor if any water is in the bag ? I am working on a large 5 bed house on a insurance job this is a more typical install I have to add I didn't install it but I know the Engineer who did

 

[milleniumaire]

"We also had underfloor heating installed in our kitchen, the manifold is in the garage under the house. "

I thought it was necessary for a UFH manifold to be installed ABOVE the UFH pipes that it supplied? Usually, the manifold has an auto air vent, but if this is below the underfloor heating, it wouldn't have any effect as air rises to the highest point, possibly to the top of the towel rails.

I assume the affected towel rails are at the highest point in the heating system?

What would happen to an auto air vent on an UFH manifold that was installed lower than the UFH? Is it possible air could get into the system? I suspect not, but this is the only thing that jumped out at me regarding your setup.

 

[John.g]

Some towel rads also have electric heating elements which have been known to draw air in via the rubber gaskets.

 

[ShaunCorbs]

Aslong as it’s purged of all air the ufh will work fine if the pipe is above the manifold

 

[Sammy1]

Aslong as it’s purged of all air the ufh will work fine if the pipe is above the manifold

Thanks all, after letting the air out of the towel rails several more times the problem seems to have resolved. I think it may have been air trapped in the system from the installation but will keep an eye on it.

 

[John.g]

Thanks all, after letting the air out of the towel rails several more times the problem seems to have resolved. I think it may have been air trapped in the system from the installation but will keep an eye on it.

There have been numerous posts about air collecting in towel rails, is it because the top(s) of the towel rails are generally higher than any other rad top(s)?.