Outdoor pizza oven for multi-purpose use

Few issues I see....

#1. Bare copper will not be happy or long lived burried directly into any type of concrete which is highly alkiline and corrosive, porous to humidity all that will corrode the pipes if installed raw. Plastic coatings or tubes will not survive those tempratures.

What tempratures you get on the outside are going to be very dependent of the thermal mass of the oven, and how long its actually in operation.

I can not predict a number.

#2. It is important to use the correct materials....and procedures. I know several people that have these, and several use them several times a week. You can't make a great pizza without a wood fired oven no matter how good the recipe is. Now these people I know, four are in Italy, one is in the USA, and that one was built by a Portugese Stone Mason I know for a friend. That doesn't see much use.

The ones these people have aren't in the 700 - 800 lb range. They are in the range of tons.

#3 with any tubing you will have the very serious issue of thermal expansion to deal with......and the risk of cold spots from it as you suspect might be enough to enduce cracks even after being fully cured.

I've considered building one myself....I just haven't been able to justify it due to the time it takes to get hot and the real ammount we would use it.

With a metal grate you can grill fantastic steaks in one too.

Most of these are used while the fire is still burning......its brought up to temp with a fire in the center, but once hot, the coals and fire are pushed to one side and maintained to keep it up to temp.

Yeah, I've seen these in opperation for a number of years in Europe.

That is what I was afraid of with the copper tubing. From some of the plans I've seen there is an insulating layer over the masonry, what if you were to just wrap the tubing on the outside? Could you get, say 5-8 years (depending on useage of course), We still don't know what the temps would be but I may just have to experiment with that. Yes the ones I have seen take up a large chunk of back yard but the one I saw at the market was rather small (4' x 4') on a 10' trailer if that and he was carrying wood and extra storage. Thanks

You have decided to try to adapt a pizza oven to heat water?????????

Water that's over a 100 feet away? The elevation doesn't bother me, what you pay for pumping up comes back down for free.

It's the distance and resulting friction loss that worries me. So, does the friction loss of pumping offset the heat lost by radiation and conduction? You are trying to keep the water warm, right?

The flow rate won't be that high, 3 to 5 gal/min. I was thinking 1/2" to 3/4" PEX on the long runs with 3/8 tubing in or around the oven structure. I'm trying to determine if the oven will be hot enough from a continuous firing that it could generate 120 to 150 degree water from the heat on the outside surface of the oven (under insulation of course). I figure I'll lose 10 to 15 degrees in the transmission. Will friction losses be that great at that low of flow rate? Will friction losses effect the heat loss or just pump efficiency?

Ok,

Start here,

One wooden match produces roughly 1 BTU. 1 BTU will heat one pound of water one degree F.

Once you determine the losses and thermal mass of your oven, you can do the math for the rest of the system.

The outside of your fire brick will be only slightly above ambient temperature, resulting in low heat input to the water. You could put a coil of metal tubing on the inside surface of the oven, but you will have to make sure there is enough water flow so that the water doesn't get so hot as to melt other piping/tubing in the system. Not impossible, but it will need some design care.