Aquahot Circulation Pump Motor Brush Replacement-Resolved

[Bruce Sieloff]

The zone A circulation pump in my Aquahot is not working. The pump is a March 809-BR. When zone A is on I have power to the fuse, power through the relay and power to the pump. In loosening the two long screws holding the aft housing to look at the motor contacts I noticed that the pump started running, and would do so when I jiggled the housing up and down, presumably creating a better contact inside. I pulled the cover and the "brushes" which had about 5/16 inch left on them and cleaned the amature contact (no contact cleaner I used 70% alcohol) and blew all the loose brush material out. Still no love. The brushes are simple rectangles of "carbon" at the end of a spring and contact. I am thinking about replacing them, they are available. Unless it's a cold solder joint making a sudden appearance I'm out of ideas. A new pump is $262 ($800+ from AQH) and I am loathe to replace it if a fix is simple. Has anyone had a similar experience?

[Keith Moffett]

Please keep us updated here as I for one have a similar problem.  Good luck!

[Gerald Farris]

Keith,
In your production era, AquaHot was using a pump with a magnetic drive coupling that was very prone to failure. There is a very high probability that your pump problem is related to the high failure prone coupling instead of pump motor brushes.

Gerald 

[Bruce Sieloff]

Apparently something as simple as a brush replacement is unavailable. My cynical side says that it is more profitable to sell a new motor than repair an existing one, but that's just me. This is the response I received from the vendor I contacted:

We get many requests for motor end bells and/or brushes but unfortunately March, and most other manufacturers, no longer sell them.
It's apparently a liability issue for them and on marine pumps changing brushes voids the US Coast Guard certification for ignition protection.
Also over the years they have changed motor suppliers back and forth a few times so there is really no sure way to even know what brushes would fit.

The few brushes we have left over are very old and actually there is no list of what pumps they actually fit.

Since I have a considerable amount of "brush" contacting the armature my next attempt will be to look for a broken wire or cold solder joint. I will have to buy a soldering iron but will report on any results. A real shame that a motor engineered for replaceable brushes is overridden by other concerns. 

[Bill Lampkin]

In Olden days, 'bout every town had a Starter/Generator repair shop. If you can find one, they will have brushes galore.

[Michael Peters]

I just a month ago replaced the same pump. Tired of screwing with it. $300 fixed it. I've got about 70 hrs of use since then with zero issues. By the way I have almost 4000 hrs on my Hurricane. I tried swapping the engine preheat pump first,but I still had the same waterpump fault shutdown issues.

[Bruce Sieloff]

Motor Issue resolved. After loosening the motor cap and getting the motor to kick to life with the furnace in ON mode I took the cap off the March circulation motor and exposed the armature contact the brushes ride on, cleaning it up a bit with some 600 grit sandpaper to expose nice shiny copper surface. I hit it with a bit of contact cleaner and reassembled it. I now have a working motor and after turning on the diesel burner I get heat from the front most vent immediately, the kitchen vent and fridge vent a minute later. I had previously purged the system of air bubbles. I will claim this portion of the repair a success.
Eventually replacing the brushes will mean a new motor or a long hunt for similar replacements but there is sufficient meat on the brushes to make that a farther down the road issue. Popping the cap was no big deal, just two screws and after removing both brushes last time and fighting a blind installation to get the rearmost brush back in I removed only the forward brush and wiggled the rear back in place when I put the cap back on. More better install technique. Not often I get success with this kind of thing so a nice Irish Coffee is in the offing.