convertng to gas, vent issue

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I have a late 70's home with an electric water heater (original!). I've decided to convert to gas a water heater as I am bringing in gas for heat and cooking anyway. I've also decided to move the heater down to the crawlspace as the mechanical/laundry room is pretty small. It is common practice here in Montana to place water heaters there in new construction, so venting can be planned from the start. Because I'm retrofitting though, I'm not sure about venting. The heater I got is a 75 Gal. 75,000 btu Standard vent unit. I have a 2x4 wall I could vent through, but I've read that 75,000 btu is too much for that wall space. I also have a 2x6 wall I could vent through, or should I just run up through my laundry with type B vent? Also, my shortest horizontal run would be 12 feet if I tried to go straight out the side of my crawlspace, too long with no room to rise. One other question, is that since the space is only 4 feet tall, I'll have to dig to fit the heater in (again common practice here), the only problem I see here is draining the heater, are there any other downsides to this type of install? Thanks. :thinker:

[DUNBAR PLUMBER]

There are numerous problems to this install.


For one, draining would be a big issue, another would be the fact that the mechanicals of the top of the heater will have to be removed just to take the heater out.


I would say that a tankless water heater would be great for the situation you have.



Double-wall B vent can be run through an approved chase inside the home or it can be run outside and up the side of the roof line with the proper brackets.

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Thanks Dunbar Plumber.

I did think about a tankless heater for a while, but because of both the cost and questions about the ability to raise water temps in volume (cold water temps at faucets here are 45-50 degrees), I opted for a quality traditional heater. Which I got a great deal on.

As for my venting question, if I do move my heater "downstairs" I will build a chase for the ''B" vent. Also to answer to the issue of moving mechanicals, I'm going to convert to "Pex" tubing at the same time as it will ease the job of rearranging the layout of both of my bathrooms later, and yes I can rent the required tools to work with the "Pex" from my local supplier. :)