Frustrating problem with my 3 year old water heater

[C5RAP]

I have a Bradford White 75 gal. “through the wall” high efficiency natural gas HWH that has been in service for three years.

The heater is short cycling, in other words, it will ignite then quickly shut off then re-ignite over and over until assumable the water reaches the desired temp.

I called the plumber that installed this unit when the house was constructed for repairs. The heater works normally when disconnected from the vent pipe but not when properly connected. The first thing that he ruled out was any obstruction in the PVC vent pipe. At this point, it was determined that it was probably the blower assemble and after waiting for a replacement to arrive, that was replaced but it didn’t correct the problem.

Now they want to replace the 3” PVC vent with 4” even though the manual doesn’t list that as an option. The length of the vent pipe is approximately 8’ with three 90s and one 45 elbow. According the manual, this seems to fall within the manufacturers guidelines. I understand that the larger pipe will mean less restriction and hopefully eliminate the problem however, not only was this system designed to work with a 3” vent, it worked well for three years. :wall:

This has been going on for at least two weeks and I really don’t like to keep this operating in such a way for this long. I worry that some other part will could fail because of it.

What do you think might be the problem?

[594tough]

If the unit worked properly before and now does not, then I would suspect a problem in the control circuits. Contact the manufacturer for advice and troubleshooting assistance.

3 90's sounds like a lot, but if the install specs allow it, OK. Double check with the manufacturer that this is not part of the problem.

[DCrio]

I have the same problem with my 9 yr old Bradford White TTW1 40gal. It worked for years and is now exhibiting the same problem. The flame keeps going out and the igniter keeps lighting it... over and over and over. Fortunately, it rarely has left us without HW but that's only because we don't use more then 40 Gal at any one time. Recovery takes hours at 5 to 30 seconds at a time, over and over... click, click, click... My guess is, the Robertshaw SP845 Electronic Ignition Module but I'm not sure. It sells for between $111 and $177 but I'm afraid to buy it on a guess for a 9 year old heater. Many will say I've got my money's worth in 9 years but I know of many HW heaters lasting 15 - 18 plus years. I have seen a couple of others in this forum with the same problem (another Bradford White and some other manufacturer). One mentioned that Bradford White knew of the problem and would replace the part free if the heater is less the 6 years old (assume that was the original warranty). Good luck!

[noroomsforme]

many bradford white control self diagnose problems need owners manual and see if any lights are blinking. If they didn't dumb maintenance men would never figure it out. There isn't that many parts on water heater that can break. That control is only thing i dislike about those water heaters if tech comes out $200 for board and $200 labor.