Boiler non-return valve.

[ebeneezerParticipant @ebeneezer]

Hi, l’ve started work on my first boiler a 3 inch vertical gas fired model.Having just machined all the thread bushes and drilled the holes for them. I have a question, one bush is for steam outlet and one is for a no-return valve. The steam outlet is positioned in the top along with the water filler and safety valve, the non-return valve is positioned two thirds of the way up the side of the boiler. Does the pressurised steam get piped to the steam outlet and does the returning exhaust steam get piped through the non-return valve back to the boiler? Could someone please enlighten me.

cheers ebeneezer

[Clive Brown 1Participant @clivebrown1]

The connection on the top of the boiler is indeed for the steam outlet, often via a control valve. The non-return valve, often called a “clack valve” is to allow water to be fed into the boiler under pressure from a pump, or possibly an injector. Exhaust steam cannot be piped directly back to the boiler but condensate could be pumped as per feed water.

HTH

[BazyleParticipant @bazyle]

Hopefully you have some instructions for the boiler that have ensured you used bronze for the bushes and not brass and are aware that it will need to be silver soldered not using plumber’s solder so will need a higher heat.

Is there a Model engineering club you can join near you for direct advice?

[noel shelleyParticipant @noelshelley55608]

As has been said bronze is better for bushes but such a small boiler is less likely to suffer from zinc loss but silver soldering, yes,  as it is gas fired.  The clack valve is for boiler feeding, so you do not run low on water whilst running, to do so will destroy the boiler. A hand pump is most likely and simple to make, an injector would feed to fast for such a small boiler. Noel.

[ebeneezerParticipant @ebeneezer]

Thanks guys it’s all clear now, just need to practice my silver soldering now.

[ebeneezerParticipant @ebeneezer]

Thank you for that. It’s all become clear now.

 

[ebeneezerParticipant @ebeneezer]

Is there such a thing as a single ended union drawing pdf out there I fancy trying to make my own.

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