I have had my first attempt to mount the cylinder block assembly on my Allchin boiler. The boiler had a slight depression where the intermalreinforcing has been silver soldered during construction. This means that it is not possible to get a perfect fit between the cylinder saddle and the boiler. I used Hylomar red joint sealant without a gasket but the joint leaked badly at low pressure. I would welcome advice on getting an effective seal.

I also have minor leaks in the joint between the slide valve box and the cylinder assembly. to seal this I will have to remove the cylinder block to get access to the lower internal screws and start again. This can be a permanent joint. Has anyone tried soft soldering this joint? I see a very frustrating time trying to seal this joint and only finding out after remounting the cylinder assembly. It would be a shame to get the main saddle joint to seal and be left with a leak from the valve box seal.

Has anyone found a way of testing the cylinder/valve box assembly before remounting on the boiler?

Thanks, Malcolm