Sunday, January 27, 2019

First major boiler repair since I installed it in 2001

The solar augmented heating system I designed and built for my workshop back in 2001 has performed very well (details on my web site).  Maintenance has been minimal as far as the equipment itself is concerned the only part that failed was a pressure tank in 2010 which was easy to replace.  The boiler is only used to augment the stored solar heat in the 40 gallon storage tank so it rarely is running full blast.  It just needs to add enough heat to bring the temperature up to 140F for my radiators.  On a typical sunny day in winter the water in the storage tank is over 150F by the late afternoon.  As that gets drawn down to about 110F the boiler makes up the difference.

A week or so ago I noticed that the exhaust blower for the Bosch Aquastar boiler was not running and my utility room was hot and smelled like propane fumes.  The heat was due to the stalled motor that was getting really hot.  The bearings had seized so it could not remove the hot exhaust.

The Aquastar boiler itself has only required minimal maintenance over the last 18 years - good German engineering.  The blower motor has 22545 hours on it.  I know this because I put an hour meter on it to log running hours.  That's equivalent to 2.6 years of continuous operation!

I had to cut the blower off the motor shaft with a sawzall because the lock screw was frozen.  It took me an hour or so of web research to track down a replacement blower motor from one supplier and a motor from another source.  The parts cost less than $150. 

Removing it and replacing it required just a few bolts and screws, and wiring the new motor in.  The wiring in the control box was a total snake pit, but the motor only has 3 wires, so it was not too daunting for a skilled electrical engineer like me.

The new blower runs much quieter because the crud that had built up in the old one was making it run out of balance and it vibrated.
I enjoy repairing and maintaining the system that I designed and I hope that it will continue to work for many years.  Click here or on the image below to see live performance of the system.
solar heatinf system diagram

If I could afford it I would replace the solar collectors and storage tank with an air source heat pump and keep the boiler and radiators as a backup.  Heat pumps are better bang for the buck these days.  Solar collectors for building heating are no longer cost competitive both from a performance standpoint and on and return on investment.

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