Blanking Plate Rusted off Back of Multi Fuel Stove

Nath17

Hi All,

I live in a rural property with no gas mains, I rely on a Hunter multi-fuel stove that's always been relatively trouble free.

The other night I heard a metallic thud, assumed it was the cat knocking something over and thought nothing of it.

A week or so later I was giving my stove its annual fettle before the chimney gets swept (not been in use so far this season) and noticed a lovely hole at the back of the stove above the baffle plate.

Had no idea what this was, did a bit of research and turns out it's the blanking plate for the rear flu exit, if it was going out the back (it goes out the top exit).

It looks like it's meant to be held in by 4 bolts, but these are well and truly disintegrated into rust and it's difficult to even make out the holes on the back of the stove.

So, this leads me to two questions:

Can this be fixed? I'm handy with a spanner, but don't fancy taking a hammer or a drill to my only source of heat. I'm *hoping* the existing bolts can be drilled out, the holes tidied up and re-tapped, and a new blanking plate installed with the help of some fire cement for good measure to keep it in place.

Second question: can anyone recommend any stove engineers in West/South Yorkshire (I'm based near Barnsley/Huddersfield)? I'm finding it incredibly difficult to find a company that maintains/repairs stoves, most I can find seem to just talk about installing new ones.

I've attached a few pictures for reference, two showing the plate and one showing the interior of the stove with the big hole left at the back. I'm happy to purchase a new blanking plate etc. if it can be fixed. The stove seems fine otherwise and has always passed the smoke test when swept.

Any thoughts appreciated!! Of course it decides to fall off as we approach winter!

lohr500

I guess it depends how much sound metal is left around the four lugs on the back wall of the stove.

A couple of suggestions which you would need to decide for yourself if they are safe or doable.

If the lugs are still solid, could you drill out the remains of the threaded fasteners on the back of the stove, drill right through the corresponding areas on the blanking plate and then refit the blanking plate using stainless nuts/bolts and copious amounts of high temperature stove sealer to seal the plate against the rear panel and the bolt holes through the blanking plate?

Alternatively drill a hole in the centre of the blanking plate (or two equally spaced holes)  and place a piece of thick section flat bar across the inner face of the rear wall of the stove with a corresponding hole/s. Then clamp the two together using  stainless nut/s and bolt/s, with plenty of sealer on the plate and around the bolt hole.

Nath17

Thanks, I took a bit of time tonight and got all the old bolts out and tidied up the hole with a wire brush. There’s a good bit of metal left and only surface corrosion. 

Just wondering if you know how tight the nuts should be that hold the blanking plate in place? I know the glass clips need to be finger tight, but I imagine the blanking plate nuts need to be tighter? Any ideas?

FreeBear

Personally, I'd use fibreglass rope as a seal. But if you are going to use something like fire cement, the bolts/nuts don't need to be tight. Do them up finger tight, and then nip them up  bit. The fire cement will expand and put a bit more pressure on the bolts.

lohr500

Good news on removing the bolts.

I think I would use a quality fire cement like Soudal HT as I think it would be easier to ensure you get a good seal around the whole of the blanking plate and possibly easier to install than trying to hold fibreglass rope in place. (Unless there is a recess in the back face of the stove for a rope seal to sit in.

With sealant, as FreeBear suggests, don't overtighten the bolts as this will squeeze out a lot of the sealant. Finger tight and half a turn is probably enough. You can always check them again after a few days of using the stove to make sure they are still tight and the seal is gas tight. Put a bead of sealant all the way around the mating face of the blanking plate. Once the plate has been fitted, I would also run a bead of sealant around the inside between the plate and the stove for good measure. Better to go over the top and ensure no leakage. 

Nath17

Thanks for the suggestions both, the manufacturer make a fibre glass gasket which I've bought along with a new blanking plate, so hopefully that will help provide a good seal. I'll get some cement and sealant for good measure, as I need to go round the flu and neaten the cement up there. I spoke to the manufacturer who suggested doing the bolts finger tight, but I think it's probably wise to nip them up with a ratchet ever so slightly to prevent CO escaping.

It really does my head in that there's a lack of engineers for stoves, at least round where I live. I showed some pictures to an "engineer", and he said that the stove would need replacing. I'm sure he would've been happy to quote me for a new one, though! Seems there's a bit of a niche in the market for this type of thing. Suppose there's a lot more money to be made fitting new ones than repairing old ones. I suppose the pictures above do make it look quite grim, but it's cleaned up pretty well with a good, healthy amount of metal there available for the bolts to go through. Anyway!

There's no cowl on my chimney, and this is the first time I've ever noticed the soot that's collected over the summer be ever so slightly moist. I know smokeless fuel + water  = H2SO4, so I'm assuming this is the cause of the blanking plate rotting off. Will look to fit a cowl ASAP.

One other thing I've noticed; the riddle support at the back seems a bit warped. The riddle bars still sit happily and move as expected when riddled. I'm wondering whether or not to replace the support too, but part of me is thinking if it's not broke then why go looking for trouble. There's 3 bolts holding the support in place, and I imagine all of them will be very reluctant to come out. Any thoughts on this?

Sorry, essay of a post!

Apodemus

Well done on the DIY repair!  As for the riddle bar support - as you say, "if it ain't broke"...

With regards to the market niche for repairs, I'm guessing that by the time you add up call-out fees, hourly rates, overheads, parts, possibly HETAS registration requirements, etc, you  would be looking at really costly repairs for what is basic DIY-able engineering.  That might get you pretty close to the costs of a new unit, assuming a straight swap, which can be done in half an hour or so.  

Also, I think that for most stoves, by the time that parts need replacing you are often into the realms of there being more needing done to get the stove back to top condition - your riddle mechanism is a good example.  I know that when I finally gave up on my old stove and replaced it, I couldn't believe how much more heat we were getting out of the new one.  I've still got all the parts of the old one, for an eventual hobby repair, but it had reached the stage where it needed a bit of work.  Every seam was really needing to be taken apart, cleaned and re-sealed to get back to an air-tight condition.  The baffle plate was bent to the point that hot air was escaping straight to the flue, some of the bricks were deteriorated or missing, the glass and door seals were not as good as they might be and the air controls and catches needed taking apart to free them up to allow for proper re-tightening.  It was still a perfectly functional stove, but all these small age-related deficiencies add up.