Gravity fed shower air problem

[Jon]

Hi,

We have a gravity fed shower which works fine most of the time, but sometimes air gets in the pipework (in the hot water pipe I believe). Usually this isn't a problem as we leave the shower head on the floor for a few mins and allow it to clear. Since all this cold weather has been with us, the shower has been playing up more this week and the flow rate is worse and is reluctant to clear the air using normal tactics.

I can only think that there is air collecting in the hot water tank and which is causing the problems by either getting trapped in the pipework or in the thermostatic shower valve. Is there a flange I can fit to the tank which will allow the air to vent out or some kind of one way valve I can put in the hot water feed to the shower?

TIA

Jon

[edalerichard]

A surrey flange fitted to the cylinder is the best answe, about =A320. . Only thing is, you'd need to connected the shower pipework to the lower oulet on the flange and run a new vent pipe from the top of the flange to the header tank.

[Dave Liquorice]

A surrey flange will fix it but it might be possible just to adjust the =

vent pipe plumbing so it runs vertically from the top of the clyinder wi= th the feed T'd off below it. I suspect that the vent is actually T'd from =

the feed at the side of the cylinder enclosure with a horizontal section= of pipe between the top of the cylinder and this T. This horizontal section of pipe collects the air released from the water as it is heated= and then gets drawn into the system. With the vent *always* rising from =

the top of the cylinder most, if not all, releases air goes up that and = is not collected to be drawn into the system.

[Jon]

Thanks for the replies so far. Here's a photo of the current pipework showing how the shower hot feed is taken from the tank:

I perhaps change the pipework so the shower feed comes off the vertical pipe below the T, as the path of least resistance for any air would be up the pipe and out of the existing vent?! Or would the air still be sucked into the shower feed due to flow of water?

Thanks,

Jon

[Jon]

This photo with the red circle shows where I was thinking of T-ing off ...

[edalerichard]

Hi, actually you are(VERY) lucky all the pipe work is near the cylinder.I was somewhat incorrect in my first post. The lower take off from the surrey flange woul;d go to the shower feed only and the rest of the household taps/vent pipe from the top. Being as though you are going to have to drain the system I'd still go for the valve.If you ever decide to make it a pumped shower (blisss) you'd need one anyhow..I dare say a proper plumber woill be along in a bit...but I wonder if a automatic air vent fitted in the 15mm pipe via a compression "t"should solve your problem. It would be a cheaper answer

[Onetap]

On 7 Jan, 20:05, [e-mail] wrote: ...but I wonder if a automatic air vent fitted in the 15mm pipe

Nah. It would let the air out but they tend to stick open if a bit of grit gets in the valve seat. Lots of suspended limescale in DHW. They can't be trusted on heating systems.

Anyone know of ones designed for DHW?

Put the tee in as suggested; the shower is taking in water with entrained air bubbles. I'd re-do the pipe off the cylinder with a 45 degree offset to the wall and a tee in the vertical at the wall

[Dave Liquorice]

puff and advertising around it. Oh no I see a tiddly thing if I look at "Quickpost".

Yep the long horizontal pipe from the cylinder top to wall is collecting the air. The path from top of cylinder to bottom of vent pipe needs to rise all the way.

Looks to be plenty of bits of pipe and space to play with to make the pipe from cylinder to vent/main DHW rise all the way. Think I'd connect the shower feed where the current T between the 22mm pipes is and put another T into the vertical 22mm just below the insulation to take the connection from the cylinder top. This would use non standard bend angles for that pipe, so you'll need some means of bending 22mm pipe.

[Jon]

Thanks for your help guys, and aplogies for the photo c*ck-up. Won't use imageshack again.

I will certainly amend the existing pipework after your advice. Would I be able to get away with using plastic pipe for the 22mm which rises away from the tank instead of trying to bend 22mm, or would that be inadvisable or unworkable?

Thanks,

Jon

[Dave Liquorice]

Unless you can support the bend in the plastic or make it permenant some how I'd be worried about stress in the push fit joint.

You can hire pipe benders and there is an excellent guide to their use (ie how to get the bend where you want it) on the net somewhere. Don't try a spring on 22mm unless you are Hercules.

[Fred]

Or willing to have a large bend radius! It's OK as long as you have 18" either side of the bend to play with. Getting the spring out might be more fun!