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Discussion Starter #1
Hello,

During remodeling we found previous owners routed the water heater vent through an old bay window and then drywalled over it. We are wanting to open the bay window up again, but can't figure out what to do with the vent.

Technically we could drywall around just that part but don't really want to. As I understand it our two options are to bring the full flue to the outside of the house, with the same vertical run up the exterior, but I'm really hoping there's a reliable, safe way to retrofit it to a powered vent system so it can just go straight out the side of the house.... without having to replace the whole water heater. We have no idea how old the heater is since we moved in two years ago, but it seems in nice shape.

I don't think our common gas heater vent will work as a third option since I believe it's PVC...?

Will something like this work to convert our venting system?

https://www.tjernlund.com/draftinducer.htm

THANK YOU!
 

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How is that vent terminated outside currently?
That water heater requires a chimney or other method of natural draft venting to work correctly.
 

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Discussion Starter #3
It's currently a natural draft, direct-vent going up through the bay window through the roof (as the illustration shows in pink). I'm hoping to be able to convert the flue into a force air/powered vent via something like this:

https://www.tjernlund.com/draftinducer.htm

Without having to replace the water heater itself.
 

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It is not currently a direct vent. As its not a direct vent water heater. It is a natural draft unit.

While the power vent will work. You will need to check if you will have the required clearance.
 

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What stops the water heater from firing up when the power venter isn't running due to failure?

What tells the power venter to come on only during a burner cycle?

I wouldn't risk it unless there's a way to tie in.
 

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There are safety systems on a power vent water heater, you don’t have them. You might be able to duplicate them, but then you are at risk having a system that is not listed. It would be easier and safer to buy a power vent unit.
 

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What stops the water heater from firing up when the power venter isn't running due to failure?

What tells the power venter to come on only during a burner cycle?

I wouldn't risk it unless there's a way to tie in.

Thats the purpose of the WHKE gas pressure switch. Which comes with the millivolt kit.
 

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Discussion Starter #10
It is not currently a direct vent. As its not a direct vent water heater. It is a natural draft unit.

While the power vent will work. You will need to check if you will have the required clearance.
My apologies for the terminology gaff, I thought they were synonymous, appreciate the correction!

When you say 'clearance' do you mean legally or dimensionally?

Was able to figure the age of the heater is 6 years, so not sure how silly it is to preemptively replace it with a powered vent heater.... The pilot light has been going out every now and then, but I'm sure that's an easy thermocouple or sensor replacement. But if it dies next year after we drywall around the vent I'll be annoyed..

Roughneck, Taylorjm, Old Thomas all duly noted and appreciate the advice.
 

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How much clearance will you have from the vent pipe to combustible material when it’s dry walled?
How much clearance is there now?
Is that B vent?
 

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Discussion Starter #12
The flue for the water heater, as well as an added fireplace (presumably added by the same previous owner) was not done to code. The fireplace is a class A (or C) flue, I believe, with a required 2" clearance, but they butted it right up against a joist (and just cut another joist without heading it off... has a .5" sag right now). The fireplace I am bringing up to code, as far as possible at least with proper air gap and fixing the joist with proper double headers. I can't add fire barriers after the fact from my research?

The water heater flue is a class B, 1" clearance. It seems like it has enough all around it, but doesn't have any fire barriers going through floors... which I think is not to code these days...

Picture shows the fireplace flue on the left, and the water heater flue on the right .
 

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When you power vent it. The vent termination has to have proper clearance from the window. Will you have that.If not, you risk fumes coming back into the house.
 

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Most power vent water heaters allow you to have quite a bit of piping so you can avoid being near windows with the exhaust, just depends how accessible your basement is.
 

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Discussion Starter #15
When you power vent it. The vent termination has to have proper clearance from the window. Will you have that.If not, you risk fumes coming back into the house.
Beenthere & Taylor, It looks like proper clearance is 4 feet from the nearest open window, so it looks like we shouldn't have a problem clearing that. We have an open basement with lots of exit options so should be good on that front.

I did talk to an HVAC guy, though, and he said I can't use my furnace/common PVC vent (are those synonymous?) even if I had a powered unit, saying if they were both running at the same time the venting wouldn't work properly?

I thought I understood that this would be an option, but maybe I'm misreading something somewhere. Any thoughts?

Thanks for the help so far, really appreciate it
 

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Your water heater is a high temp vented appliance. It would melt the PVC.
 
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Discussion Starter #17
Your water heater is a high temp vented appliance. It would melt the PVC.
Yes, I'm sorry, I meant if I replaced my whole unit with a power vented water heater (not just retrofit), I thought it would be able to use/share the common PVC vent from my furnace. It seems like there are mixed opinions of this online so I'm not sure I understand.

Power vented water heaters are able to use PVC, correct? Because the speed of venting cools the gases down enough to be safe with that material. Natural draft can't because the gases are slow moving and too hot. But some resources say power vents can share the furnace PVC vents, while others caution against it. Anything I'm not understanding correctly?
 

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Yes, I'm sorry, I meant if I replaced my whole unit with a power vented water heater (not just retrofit), I thought it would be able to use/share the common PVC vent from my furnace. It seems like there are mixed opinions of this online so I'm not sure I understand.

Power vented water heaters are able to use PVC, correct? Because the speed of venting cools the gases down enough to be safe with that material. Natural draft can't because the gases are slow moving and too hot. But some resources say power vents can share the furnace PVC vents, while others caution against it. Anything I'm not understanding correctly?



If you were to tie the two exhaust together. When the water heater was running, the furnace would go into lock out because its pressure switch would be closed before the inducer started.


Same for the water heater if the furnace was running when the water tried to start to heat the water.
 

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Discussion Starter #20
Thanks gang, appreciate the help and added understanding! I feel better moving into making some decisions, while steering clear of the common vent, etc
 
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