Bleed Valve / Thumb Valves on Y Plan Open Vented Heat on Boiler with Indirect HWC

[wildhorses]

Hi I've had a HWC moved from one room to the next and some pipework changed but it looks like I've lost! my thumb vents / bleed values.

It's an open vented system with a heat only boiler and indirect cylinder. Basically the boiler pumps hot water upstairs to the bedroom, there is a vertical pipe that includes firstly the vent then fill then gate valve then pump then gate valve then three port value (port A going to rads and port B going to cylinder). Hope all that is standard and explained ok.

My question is I keep getting air trapped in the system, should I have a thumb bleed on the hot (top coil in) into the HWC from Port B on the three port and should I also have one on the loop from the Port A back to the heating system (as that creates a high point that could trap air - or would that be expelled through the vent on the three port valve to the HWC?.

Do these need to be on a stalk or just on the main 22mm lines. Any advice VERY gratefully received so I can work out what I need doing.

If this is unclear I can try and do a picture but it basically looks like the above below - hope this will suffice

Thanks V much


Port B below goes to the top coil of the HWC
Port A below goes to the feed back down to the central heating rads
Question is regarding putting manual bleed valves on the feeds from port A and Port B
Only showing flow below and not return


Three port v |||
...................|
.........gate v |
.........pump O
.........gate v |
...................|
........fill ------
........vent ----
...................|
...................|
...................-----------
................................|
................................|
................................|
................................Boiler

 

[Simon F]

some pictures would be helpful.
you say you keep getting air in,
how did you vent in the first place?
is the air being pulled in?
previously was you venting the system often?

 

[stevebush]

this in my view is the most annoying method of configuring a Y Plan installation, but in answer to your question you will need 'thumb vents' on any high points in pipework, i always put them on about 200mm pipe stems, it collects more air than short stems saves bleeding every two mins, is this a new installation, thought this method went out years ago, you can put them on both supply pipes after valve but normally just on cylinder side & let heating vent though valve, easy to put right couple hours tops, just remember to put a good inhibitor back in system, steve

 

[stevetheplumber]

if its installed properly you shouldnt need vent points but if you need them as said on stalks i use 22mm ones rather than reduce down

 

[wildhorses]

this in my view is the most annoying method of configuring a Y Plan installation, but in answer to your question you will need 'thumb vents' on any high points in pipework, i always put them on about 200mm pipe stems, it collects more air than short stems saves bleeding every two mins, is this a new installation, thought this method went out years ago, you can put them on both supply pipes after valve but normally just on cylinder side & let heating vent though valve, easy to put right couple hours tops, just remember to put a good inhibitor back in system, steve

thanks Steve for your comments, can you explain a bit about why this is the most anoying method of configuating the system, I'd just like to understand in case I can make a few changes in the layout while I'm getting the other changes done. It's not a new install more a reconfiguration. would be glad of any comments you can make. I'll get one put on the cylinder flow. There is a elbow that goes 90 in to the top coil or the cylinder so if I just add a 't' instead of the elbow and a 20cm bit of 22mm copper with a 15mm thumb on the top would that suffice. I'll also get the angle of the outlet pipe changed a little that flows back to the central heating flow so the air trickles up towards the three port and up to the HWC thumb valve - would that be ok you think?

 

[wildhorses]

some pictures would be helpful.
you say you keep getting air in,
how did you vent in the first place?
is the air being pulled in?
previously was you venting the system often?

had a really grotty auto bleed valve in previously but in the reconfig it's just gone, I think the air is from the changes but I'm interested to hear what SteveBush says in case there are other changes that will help keep it out, thanks for your help

 

[wildhorses]

if its installed properly you shouldnt need vent points but if you need them as said on stalks i use 22mm ones rather than reduce down

thanks for your comments, How does the air come out from the initial reconfig and fill if I don't add this vent to the HWC coil as it represents a high point in the system. I have a close coupled vent and feed but this lower than the HWC.

 

[stevebush]

if its how you have drawn it the vent & cold feed are teed off the vertical pipe leading to pump & 3 port valve, this means that you have to use some sort of bleed valve to get rid of air on fill up & also causes problem later in life when system starts to gas up, if it was me i would rip it out & put in classic H configuration, i know the H way is not the preferred method in manufacturers instructions but does work well, i also prefer a combined cold feed & vent, but if you use separate cold feed & vent they must be with-in 150mm of each other to stop pumping over & sucking air in, keeps them both neutral,all this & more can be found on line or in a good book, still got mine from collage, still use them, over 20yrs old now, should up date i guess but being a plumber hate spending money when old will do... steve

 

[wildhorses]

if its how you have drawn it the vent & cold feed are teed off the vertical pipe leading to pump & 3 port valve, this means that you have to use some sort of bleed valve to get rid of air on fill up & also causes problem later in life when system starts to gas up, if it was me i would rip it out & put in classic H configuration, i know the H way is not the preferred method in manufacturers instructions but does work well, i also prefer a combined cold feed & vent, but if you use separate cold feed & vent they must be with-in 150mm of each other to stop pumping over & sucking air in, keeps them both neutral,all this & more can be found on line or in a good book, still got mine from collage, still use them, over 20yrs old now, should up date i guess but being a plumber hate spending money when old will do... steve

Thanks Steve

I see where your going, so I think I'm ok on the close coupled thing the vent and fill T's are practically touching so could not get any closer, they were combined a while back but separated as boiler manufactuer wanted separate fill for safety reasons, I realise there are many views on this, but being within 100cm should stop pumping over etc. I have plenty of space on the port B pipe going to the top coil of the HWC to add a bleed and large stalk so I'll do that, I've less space on Port A to pipe to the central heating maybe a 10cm stalk would fit, is it worth adding this one or just rely on the Port B one. ?

many thanks

 

[wildhorses]

p.s. you hit the nail on the head the air came from a drain and fill with inhitbitor....

 

[stevetheplumber]

basicly you should always go high and then drop down to the valve allowing any air to escape up the vent and feed