Vitcas 140 issues

[oblertone]

A friend is struggling with a newly constructed wfo from Vitcas in that he cannot seem to get it to a reasonable temperature; compounded by somewhat confusing instructions from the supplier.

This info is coming via another forum so any losses in translation are mine alone.

The oven is reportedly a Vitcas 140, internal: 800mm wide x 1,400mm deep x 400mm high Weight: 500kg 

The 100mm diameter flue has a damper and the oven is supplied with a fixed external door which has adjustable vents.

The fuel used initially is kiln dried ash.

Verbal instructions from the supplier do not reference any 'curing' or drying out fires rather "...  the manufacturer suggested building a big very hot fire for the first firing."

"Not what the manufacturer says. They say to start the fire and keep the door closed except for refuelling until the oven is up to temperature."

"I've told the manufacturer I'll give it one more try. They asked what wood I was using I told them kiln-dried ash. They say this is no good and suggested I used only kiln dried oak. I now have a load of that and will try again. I've also ordered another metre length of flue-pipe, see what difference that makes. Not much I can do about the diameter."

I have suggested a 'curing' routine but this appears contrary to manufacturers instructions; other than a very small flue as supplied has the collective any thoughts ?

[fox]

Never heard the likes before, sound like a load of rubbish!
Perhaps they are thinking you can light a fire and close the door so the fire goes out and just smoulders into charcoal but It just does not make much sense !
I would go for the normal slow small fire, building up every day for 5 days.

[truckcab79]

Id ignore the manufacturer and go with either your suggested method or the Forno Bravo one.

www.fornobravo.com/pompeii-oven/curing/

As for kiln fired ash being no good that’s obviously nonsense. Use nothing else in my oven and recommend the same to clients. No issues with getting to temp. To be honest if you shoved enough of any old crap in there it should still get to temp.

[stolzy]

It is I who is having the problem with the Vitcas 140. Ignoring the often conflicting advice from the manufacturer, I have persisted with this oven. Lit today with much the same result, lazy fire and loads and loads of smoke coming out of the door (rather little from the flue). there is so much smoke that the garden is uninhabitable whilst the oven is lit.

The fire seems to have none of the energy that I see in videos of pizza ovens. I have the impression that it's not getting enough air

I've been monitoring the temperature and most of 4 hrs has got it just over 250C.

I've ordered a longer flue, but I'm skeptical it could make that much difference.

[fox]

Can you post some pictures, that would help no end.
Wet ovens will smoke but you most certainly dont want to be closing the door with a lit fire.
Without knowing how you have built the oven we cant offer much more help.
What sort of insulation have you used?
Has the oven been built as an igloo design?
Have you left a steam release exit in the top ?

[stolzy]

Aug 1, 2021 12:27:24 GMT fox said:

Can you post some pictures, that would help no end.
Wet ovens will smoke but you most certainly dont want to be closing the door with a lit fire.
Without knowing how you have built the oven we cant offer much more help.
What sort of insulation have you used?
Has the oven been built as an igloo design?
Have you left a steam release exit in the top ?

This is the oven.

Oven is assembled from a kit of concrete parts.

No insulation as yet because there is a significant chance it will go back for a refund.

No steam release.

[fox]

Ok well without any insulation you can not expect the oven to work as it is designed to, also you should not even attempt to cure the oven without insulation as it will cause uneven heat spots and very likely cracks will form!
I see what looks like 50mm of ceramic insulation under the floor, that is bare minimum and would be better with 3-4 inches.
The chimney outlet is I believe only 100mm as is the flue, you really need 150mm for the flue even if if you cant enlarge the chimney exit..
The door mush always be open when the fire is lit.
I have searched  the net to find info on the Vitcas range although I think there is a thread on this forum.

[stolzy]

Aug 1, 2021 14:18:39 GMT fox said:

Ok well without any insulation you can not expect the oven to work as it is designed to, also you should not even attempt to cure the oven without insulation as it will cause uneven heat spots and very likely cracks will form!
I see what looks like 50mm of ceramic insulation under the floor, that is bare minimum and would be better with 3-4 inches.
The chimney outlet is I believe only 100mm as is the flue, you really need 150mm for the flue even if if you cant enlarge the chimney exit..
The door mush always be open when the fire is lit.
I have searched  the net to find info on the Vitcas range although I think there is a thread on this forum.

Again, I suspect the info from Vitcas may be at fault since they specifically told me to fire the oven several times before  adding the insulation.

The insulation (correct 50mm) was an optional extra.  Normally there should be none (according to Vitcas).

The flue is 100 mm.  No option to increase it.

Again, Vitcas say the door should be kept closed, but the vents open (the fire goes out immediately in this condition).

Hard to now what to do when the information from the manufacturer appears inconsistent and often plain wrong.

I plan to give it one more try with a longer flue and if that doesnt work, they've agreed to come and collect it for a refund (no small feat given it's weight and bulk)

[truckcab79]

They are right about firing without insulation as this will allow moisture in the casting to escape more easily. However for the sake of not allowing more moisture in, particularly to the exposed insulation board underneath, I assume that you are keeping it covered once cooled, and between firings.

Door definitely needs to be open. There will not be enough flow of air to keep it lit and hot otherwise.

If they’ve offered to refund and collect it that’s very fair. Assuming you are using enough decent dry wood I cannot see any reason that it will not heat otherwise. Yes, the flue is a little small but it’s not like they are some fly-by-night manufacturer selling a product that does not work. (At least for everyone else presumably). I’d give it another go and then take them up on the offer and look for a different manufacturer. At least you haven’t insulated and rendered it so no great loss long term.

[truckcab79]

Not being patronising but we’ve all made stupid errors. Have you checked that the flue is in the open position? On my oven, unless you know, it’s not clear from the handle position whether it’s open or closed. Would be easily done. (By me at least!).

[stolzy]

Aug 2, 2021 12:13:28 GMT truckcab79 said:

Not being patronising but we’ve all made stupid errors. Have you checked that the flue is in the open position? On my oven, unless you know, it’s not clear from the handle position whether it’s open or closed. Would be easily done. (By me at least!).

It's definitely open.

[stolzy]

Aug 2, 2021 5:39:16 GMT truckcab79 said:

They are right about firing without insulation as this will allow moisture in the casting to escape more easily. However for the sake of not allowing more moisture in, particularly to the exposed insulation board underneath, I assume that you are keeping it covered once cooled, and between firings.

Door definitely needs to be open. There will not be enough flow of air to keep it lit and hot otherwise.

If they’ve offered to refund and collect it that’s very fair. Assuming you are using enough decent dry wood I cannot see any reason that it will not heat otherwise. Yes, the flue is a little small but it’s not like they are some fly-by-night manufacturer selling a product that does not work. (At least for everyone else presumably). I’d give it another go and then take them up on the offer and look for a different manufacturer. At least you haven’t insulated and rendered it so no great loss long term.

They've rescinded their offer to take it back, apparently because it's been used, they now (contrary to their previous statements) can't take it back.  It having been used apparently revokes my Sale of Goods Act (or whatever it's current incarnation is) rights.

They now won't provide any help at all, merely pointing me to YT videos on how to start a fire and such like.  They clearly just want to kick the problem into the long grass and presumably hope I'll get fed up with it.

So I've started a MCOL action as well as a GDPR subject data access request which should provide some useful evidence.

As to their customer service: Thursday 11 calls, 1 answered. Friday 27 calls, 2 answered, Today 31 calls, 1 answered.

[truckcab79]

Well as someone who spent 27 years as a Retail Director I can assure you that they cannot claim your use as a reason not to refund. You are entitled to reject it if it is faulty or otherwise not fit for purpose.

In fairness to them however I’m not sure how it can be faulty as it is really just a glorified concrete shell in which you are trying to set fire to some wood. It can’t really not work.

Start from scratch or get someone else to do it for you. Maybe you’re too close to the issue to see the problem.

Are you using the upside down method or whatever it’s called? Stack of logs about the thickness of your wrist. 8 maybe, stacked Jenga style with a space through the middle. Kindling at the top. Twisted newspaper or your choice of fire lighter in the centre. Light the firefighters. They’ll catch the kindling. Boom. Up it all goes in flames. Smoke for a minute or two at most and then when the flames get going and roar up the flue, no smoke and you should be up to full temp maybe an hour later. (Depends very much on your own oven that last bit).

And definitely door fully open or taken off. The fire needs oxygen.

[fox]

Oh …well if you decided to keep the oven I am sure it can be made to operate just fine!

The problem is when a high mass casement is heated without any insulation the heat will not be evenly spread and the top of the dome will become much hotter than the the sides.
Unfortunately this then causes different rates of expansion and can very easily cause cracks to form!
Once a layer of insulation is applied, then the heat will be spread all around and start radiating back into the dome, in turn air is being drawn into the dome through the door opening. The air is then super heated and goes back out and up he chimney.

That is the principle operation of a dome wood fired oven.
It quite simply wont work efficiently without insulation.

If I recall correctly one of the issues with this model is the small diameter chimney, however you can retro fit a larger 150mm chimney and even though the exit will still be 100mm the bigger flue will help a lot!
Good luck with whatever happens .

[stolzy]

Aug 2, 2021 15:35:00 GMT fox said:

Oh …well if you decided to keep the oven I am sure it can be made to operate just fine!

The problem is when a high mass casement is heated without any insulation the heat will not be evenly spread and the top of the dome will become much hotter than the the sides.
Unfortunately this then causes different rates of expansion and can very easily cause cracks to form!
Once a layer of insulation is applied, then the heat will be spread all around and start radiating back into the dome, in turn air is being drawn into the dome through the door opening. The air is then super heated and goes back out and up he chimney.

That is the principle operation of a dome wood fired oven.
It quite simply wont work efficiently without insulation.

If I recall correctly one of the issues with this model is the small diameter chimney, however you can retro fit a larger 150mm chimney and even though the exit will still be 100mm the bigger flue will help a lot!
Good luck with whatever happens .

I've tried that method too.  Getting the fire started isn't so much of a problem as the lazy fire that results.  I've even tried a leaf blower to get it going and it does.  Until you turn the leaf blower off and it returns to the lazy smokey fire again.