Protecting wood-fired boilers from low water temperatures

[Kelster]

Here's a link to a great article on using a thermal clutch and why it's important for safety and boiler longevity:

(broken link removed to http://biomassthermal.org/news/hydronics2.asp)

 

[BoilerMan]

Everyone on this forum should read Siggy's book. There would be fewer threads with questions though........

TS

 

[hobbyheater]

Our first boiler was like the one in this picture and had all the problems associated with low temperature combustion.


Our second was a cast iron triple pass with downdraft combustion and had all the problems; low temperature combustion wall, low temperature fire and when storage was added, it was still a creosote nightmare. In the early 80s not a lot was known about return water protection.


The Jetstream after 30 years has no creosote issues and has never operated with return water projection. The loading tube passes through the heat exchanger where the lower temperatures quench undesired combustion.
This picture was taken with the boiler at full output - my favorite picture! Just warm, odor free air.

The chimney after 2 months of operation!

I'm a believer in Gasification with storage.
The PDF is from the Jetstream manual - old stuff but still relevant.

 

[hiker88]

I have a temperature gauge on the "return from load" port (port 3 I believe) on my termovar. I couldn't believe how much the temp there would drop when my circulator pump first kicked on. I think it might have been 10 or so degree celsius. You can put your hands on the pipe and feel that slug of cold water being bushed ahead of what is coming out of the boiler at first. It's pretty eye opening.