Power vent WH or wall mounted vent fan??

[H2oheartny3]

I need to replace my gas water heater and have a few questions...

My boiler(hot water heat) and current water heater share a vent outside. There is a vent fan mounted on the outside of my house that is switched on when either the WH or heat turns on. I’m guessing there is a gas pressure switch installed on the water heater(looks like it was installed b/c of the shared vent??) the questions I have are #1 is this legal or do they need to be vented separately?? #2 if they do have to be separated does this mean I have to get a power vent water heater since I can only vent out of the side of my house?? Thanks for any help!!

 

[breplum]

Power vent water heater is likely the correct solution.
Common venting two power vents is not proper.
Power vent WHs are expensive these days.
You might consider a tankless like Navien that power vents using 2" PVC, lasts longer (easily twice as long), and is highly efficient (96%).
In your case, a Combi boiler/WH might be the ticket.
I bet your boiler is not 96% efficient.

 

[H2oheartny3]

If I got a power vent water heater I would vent it separately. That’s what I’m asking if it is ok to common vent the two together if they share the one fan and control it individually. If it is I’ll just get an atmospheric vent with a pressure switch to kick on the vent fan. I do like the idea of the combo boiler!! I’m guessing they’re tankless/wall mounted?? My boiler is old, but runs really well.

 

[breplum]

You can combine two pieces of equipment if you follow the mfrs instructions and have all the required safety pieces ( purge relay/timer, gas pressure switch, thermocouple junction adapter, linear limit spillage switch) look up Tjernlund. In the end you still have low efficiency and only average reliability.

 

[TomFOhio]

Most power vent water heaters are vented in plastic. Vent it separately. Read the manual on distances from other objects where it terminates outside. Read the venting part good also. It tells the pipe size and how many fittings you can use inside the house.