Hi, I am replacing a Hayward millivolt H250 pool heater installed in a shed and vented vertically. The new heater is a Hayward H250FDN negative pressure venting. The old install had a huge draft hood and I cannot find anywhere if the new heater requires a draft hood or wetherIMG_9502.jpegIMG_9503.jpeg I run B vent directly from the heater?
I would like to keep the current B vent installation which is 7". The new heater negative vent adapter has a 6" C vent adapter. Can I run C pipe from the heater to a 6" to 7" increaser with the B adapter to tie into the existing vent?
The indoor draft hood used with the H250 is not used with the H250FDN.
If the heater is in an unconditioned space you must install B-vent from the water heater to the existing B-vent.
I understand the draft hood from the H250 is not used with the H250FDN. I assumed that there is a specific draft hood for the H250FDN. The vent kit for the FDN is just a plate with a C flange adapter. I cannot find any info on the FDN requiring a draft hood.
The H250 vent is 7" and the H250FDN is 6". The FDN is also a couple of inches lower in height. Removing the draft hood from the existing install leaves about 40" to replace and transition from 6" to 7".
I am adding an 18" section of 7" B vent below the existing elbow that leads to the tee then up and out through the roof. Directly on top of the heater will have a section of 6" C vent to make up the transition between the heater and the B vent. A 6" to 7" increaser will transition the 6" C to 7" B vent connector.
I could have had a longer 7" B section, but I used what I had. The vent sizing in the manual allows for an increase in vent diameter and the new C vent section basically replaces the old draft hood and is in conditioned space.