Hi members,

This is not car related.

I am going to repair a gas central heating boiler which has a cast iron heat exchanger with 3 steel core plugs in. I have removed the leaking one which is the cup type.
The boiler manufacturer doesn't offer this as a spare. On measuring the hole with a vernier guage it comes out at 31.9 mm. I ordered 3 steel ones online (32mm) which when arrived on saturday morning measure 32.5.
I'm going to remove the heat exchanger Tuesday morning to remove the existing 2 and hammer the new ones in with a socket of the right size.

Question before I start.

The size Of the new ones seem a little too large to fit.
I have never fitted core Plugs before even though I'm a heating engineer by trade.
What sealant should be used as some say yes and others say no.

Many thanks

Kevin

If they are too big they will distort but worth a try. Sealing compound is not needed but silicone sealant would help to lubricate the plug and then it handily goes off with a bead on the inside. Certainly cant do any harm.

How much of the heat exchange surface still exists? When mine started leaking the fire side had lost all of its heat absorbing fins so most of the heat was going straight up the flue. It wasn't worth repairing.

Thanks for the reply.

The boiler in question is a Potterton suprima and is in perfect condition.
The boiler is only 7 years old and with no inhibiter in the system has perforated through one of the 3 core plugs on the left hand side of the heat exchanger.

The job is for an oap customer and thought rather than replace the heat exchanger at £230+vat just for the part I thought I would try a repair 1st.

It was either going to using boss White or red hylotyte when pressing the new plugs in.

Should be a cheap fix go for it. Do Potterton supply spare core plugs?

Just a quick update,

I did the job last Tuesday,
Potterton don't sell core plugs as a listed part so I ordered them off eBay.
There were 5 in total, 3 on the left hand side of the heat exchanger and 2 on the right. On removing the plugs I found all five almost corroded through. The cast iron holes were in excellent condition with no pitting so all that was needed was to clean off the original sealant. I hammered the new ones in with hylotyte red. I then refitted the heat exchanger, tested and added corrosion inhibitor. Job done and one happy customer

Many thanks for the reply's
Kevin

Save the old ones to show prospective customers why they should always have inhibitor in their system.