At what temperature am I pushing my luck?

[jcg31]

It is turning cold in Wisconsin (evenings in mid 40s) and I have a long way to go. Can someone tell me at what temperature I begin affecting the strength of the mortar (I am using refrax) and any suggestions for extending the buiding season? With my schedule it is looking like the oven won't be done until mid November (providing I can continue to work).
Thanks for any thoughts.
Jim

[gjbingham]

Re: At what temperature am I pushing my luck?

Are you speaking the temperature affecting the workability during the day or set and cure overnight? Jame's may know the answer to workablity issues at low temps.

A lot of us are putting lightbulbs inside the domes at night to maintain temps above freezing, at least until the domes get fire-cured.
Hope that helps.
George

[CanuckJim]

Re: At what temperature am I pushing my luck?

JCG,

Refmix, like other mortars cannot be allowed to freeze before it has set. The mortar will still be there, of course, but it will be weak and eventually will crumble. Putting a light bulb inside the dome is a good idea, but if overnight freezing is a possibility, I'd build a tarp tent around the whole job. That's exactly what I'm doing right now north of Toronto. If sustained below freezing temps are forecast, you might want to invest in a Home Cheapo 1500watt heater to keep the tarped space above freezing. One way to defeat cold weather workability of wet mortar is to use water at about room temp when you begin your mix.

Jim

[Acoma]

Re: At what temperature am I pushing my luck?

Who has actually buillt one in the winter where it freezes? Would insulated tarps work if you are going to be working only a couple days a week on the dome? Jim, you say Refmix is not allowed to freeze before setting. How long in cold, frost, freezing areas is that? Gives me an idea of progress through fall/ winter.

[jcg31]

Re: At what temperature am I pushing my luck?

Jim,
I have a 10x10x10 EZup ($199) that is working out great, withstood 55mph gusts all last night. I will add the heater tonight. How long after aoplying the mortar do I have to worry about this?
Thanks,
Jim

[judykatherine]

Re: At what temperature am I pushing my luck?

Yikes! is this another worry? I had to knock some brick out today that I set with sairset on 10-26 because I choked down the flue size, and they were still sort of wet, (after my first bitty fire this weekend and the smoke poured out the front.) Should I still have the light/warm fan on this?

[gjbingham]

Re: At what temperature am I pushing my luck?

Smoke pouring out the front may not necessarily be due to the reduced vent size. If you don't have a chimney attached yet, the're wil be almost no draw through the vent. Also, from what I've read, an improperly built fire will cause smoke out the front even on a perfectly built oven.
G

[Mojoe]

Re: At what temperature am I pushing my luck?

Bitty fire may not have heated up the flue enough. Flue needs to get warm before it will draw the smoke up and out efficiently.

[jcg31]

Re: At what temperature am I pushing my luck?

I have resolved my mortar issue, but now that I seem to have folks here who know something about draw, that is my next step. The opening for my flue spans nearly the entire arch and measures 17 x 4.5. That reduces (plan) to an 8.5" square opening to hold an 8" collar. Laying brick on this this weekend. Am I on the right course?

Thanks,
Jim

[Mojoe]

Re: At what temperature am I pushing my luck?

I started with 20" span but used angle iron supports for brick and reduced to 8.5". I get some smoke, not billowing, from the front upon firing but once the flue gets warm ( +/- 5minutes) all the smoke is up and out. I was simply amazed at the flues function, couldn't take my eyes off it on the first few fires.

Check out the chimney section from the free pompeii plans.