Water Heater Challenge

[jd_ohio]

Hello,

I am new to the forum but have found it extremely helpful in posts I have reviewed in the past. We recently purchased an 1850s farmhouse that has a gas storage water heater in the basement and a gas tankless unit on the second floor serving a single bathroom. There are two because the way the house was built there was very limited space to run plumbing to the second floor, and there is no single vent stack running through the house. The tankless unit has a single stack from the second floor to the roof.

Here is my challenge. The basement storage unit does not vent properly as it runs out the basement under a deck off the house. I know this is an issue and I want to remedy it. The problem is that I cannot properly vent any gas unit from the basement (both standard or condensing units) and I do not want to go to electric since the farm has oil/gas well for free energy. Even going with a high efficiency unit that can direct vent poses challenges as the house has decking all around it, and running a stack up the side of the house would be extremely challenging and costly I would imagine.

One thought I had was to use the tankless unit on the second floor to serve the entire house as I do have a spare 3/4 line running between the basement and the second floor to connect back to the basement lines. If the unit is too small (currently 6 gpm) then I could upgrade this unit to a larger unit that could properly vent out the roof and serve the whole house.

Doing the math calculations for load, if I used a single tankless unit to serve the entire house, 6.5 might be pushing it but 8-9 gpm would be plenty.

Does anyone see any challenges with this solution?

Thanks for taking the time.

JD

 

[Master Plumber Mark]

Tankless basically suck......but knock yourself out
if you must install one you better have very soft water...


Why not install a Rheem 75 gallon power vented unit in the basement
and vent the pvc out the side of the home somewhere...its no tthat hard....

If you could figure out a way to get a 1/2 pex line hot line up to that
second bathroom and eliminate the tankless heater all together, ,....???

 

[Sponsor]

 

[jd_ohio]

Mark,

Thanks for the response and power vent option.

It does not matter to me if I use tankless or not, I am just trying to figure out the best solution for hot water in my situation. In terms of the power vent option, I assume there are different clearance requirements depending on the model? This is where I run into challenges when trying to vent out the side of the house...all possible venting locations are either under a deck (less than 3 ft of height clearance), or near a window or door. As I said, the house has a wrap around porch (covered on almost all sides) making it difficult to place a vent. If I ran a vent anywhere out the side of the house, it would be in an area where people/children could be located at any given time. In addition, the house sits on a sandstone block foundation that makes hole drilling a pain.

I suppose one option could be to run the vent under the deck and open it somewhere to the outside. Clearance to the ground would be 12-16" or so...

The current tankless unit has a proper vent directly through the roof...this is the major reason I was looking to use this setup. If I had the room to install a gas tank burner there, I probably would.

Thanks,

JD

 

[Jadnashua]

What do you use to heat the house? If you have hot water heat, chuck the tank and install an indirect WH. Both condensing and power vent burners have specific maximum distances and clearances about where they can legally and safely be installed. None of them, as you've found, are allowed to vent underneath a deck, but MIGHT still have enough length allowed to where they could extend to the outer edge of it, and might solve your problem. Effective length takes into account each turn in addition to the actual run length and diameter. A condensing unit often can be done in PVC, and you might find a path that could take it up some (corner of a closet?) to get it into an area where it is allowed (clearance to windows, doors, overhangs, etc.).

 

[hj]

quote; If you could figure out a way to get a 1/2 pex line hot line up to that

If he already has a line that could deliver hot water from the tankless to the downstairs, it will ALSO work to run from the basement to the upstairs.

 

[Dana]

To have better flow and faster tub filling capacity it's better to have the thermal mass of a storage tank. A stainless unit like the HTP SSU-45CB to store the water, and a half-inch loop between the tankless and storage tank using a bronze impeller pump would give you the best of both worlds- high gpm when you need it, and faster than standalone tank recovery times due to the higher burner output of the tankless.

See the installation manual. It's possible to get creative with the controls, but it doesn't need to be too messy.