Waterstone/Stanley Range - pipe diameter too small?

I've just added a range with back boiler to my existing central heating system - which is oil fired. Everything runs great until the range gets up to temperature, that's when the water hammer starts. The original piping to the hot water cylinder is 22mm and this is what I've connected the range to. I have since been told that this needs to be replaced with 'inch' piping all the way from the range to the cylinder to solve the noise problem. Is this right or is there any other solution. It's not too big a deal to replace the pipe - but I'd like to know that this is going to sort out the problem... thanks for any suggestions/solutions.

Do you have a pump on the range circuit, or is it gravity feed? If gravity you have to be careful about the pipe runs as well as the size. Seriously consider 35 or even 42mm if its gravity circulation. The hammering is boiling caused because the heat cannot get away from the boiler fast enough. This a potentially dangerous situation.

How have you connected the two heat sources to the same heating system?

The oil fired central heating has a pump. The hot water cylinder is on a spur off of this circuit and the new range is connected to this spur. I increased the speed of the pump last night (from 1 to 2) and the noise didn't come back - but then I didn't have the range piled up with as much coal as I had the first night (kid with a new toy syndrome).

The pipework throughout , from the oil burner to all radiators, is 22mm - then reduces to 15mm at the radiator. The pipework to the cylinder is 22mm to a single coil and is vented on the hot pipe to atmosphere. The range then, as I said above, connected to this 22mm pipe. The run from range to cylinder is only about four metres and wouldn't be too much trouble to replace - do you reckon that this would solve the problem?

Me not a plumber ... just in case you hadn't sussed that

Thanks for the reply and suggestions.

I would quickly make substantial changes so that nobody knew about the original set-up, too embarrassing.

You need to re-think this one as you have a fundamental hydraulic problem. You also need to ensure the heat is taken away from the range fast enough. Changing the pipe diameter is a must, and if it's gravity circulation from the range I'd use 35mm pipe. You probably need a heat leak radiator too.

To run two heat sources on the same systemrequires a cunning bit of plumbing, but you will find a solution here
then click on the layout link. This gadget is not cheap, but it will give you a sound system which will work reliably. You will have to connect the CH pump so it runs if the temperature in the range rises above say 90 deg C.

I doubt that your new setup complies even with Irish regulations.

Cheers Oilman - don't worry 'bout me being embarassed, that's the way I learn things, as long as it doesn't blow up and kill the family!

I looked at the neutraliser and the layout shown on the first diagram looks suspiciously like the one I should have. It also means that I can keep most of my original pipework in the cupboard and add 35mm feed/return from the range ... then join it all up in the attic??? Does the 35mm from the range stop at the neutraliser?

Lastly but not leastly ... does the text (below) from the information page about the neutraliser mean that the range will also be feeding into the radiator system as well as the hot water cylinder.

...... connected to the chamber can have no hydraulic interaction.
This means in effect that the pumped circuit from, say a gas or oil fired boiler will not induce flow through a solid fuel boiler via its gravity circuit.

The solid fuel boiler will, however, feed hot water into the system, thus achieving the desired objective. ......

Sorry for hassling you with more questions and thanks for the help you've already given ... looks like I'm going to be busy this weekend!!

Cheers from a cold Donegal.

Using this neutraliser - can the cold pipe from the oil fired side and the return from the radiators be a 'common' pipe or will I need to dig up this joint and pipe these flows seperately to the neutraliser?

Cheers guv