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[husky 555]

I guess I expected too much and thought that this season would be different from the last four seasons with my Shaver.  This season I started with all the modifications (i.e. ranco stat, solenoid with flapper, new door seal, and new seal on top of water tank, and even reinsulated the whole furnace). 

The other day it was about 40 - 45 degrees my house was not calling for heat most of the day.  I had the opportunity to observe my owb.  When I ran the pump 24/7  the owb would cycle about every 35 to 40 minutes (personally I thought that was too many times given the weather and reinsulated owb).  So with that, I changed the pump to run when my house would call for heat.  Basically the furnace just sat there and idled.  Now, my tstat is set to turn off at 179 which it did, however, I checked the owb 45 minutes to an hour later to find my water temp was 200 degrees.  Last year my knowledge of the furnace told me I had an air leak.  This I year believe the furnace is air tight and thought that maybe the furnace would have continued to heat an additional ten degrees before cooling down. 

There is no smoke leaking out ash door or firebox door during the burn cycle to tell me there is an air leak.  In fact, when I opened the door when the water temp was 200 degrees, there was no flame at all so I don't know how it was even heating the water. 

My fear is that when I'm at work during the days when it is 40 degrees I will risk boil over.  Maybe I should've waited before I turned on my pump to see how hot it would really get. 

As a rule of thumb it seems harder to burn an owb durning moderate temps. 

I guess I could also get a programmable t stat for my garage and set it to heat different parts of the day to pull heat of the furnace. 

Can anyone tell me what I'm doing wrong or give suggestions?

[jerkash]

You said your cut off temp was 179
What is your cut on temp??

[husky 555]

stat comes on at 168

[RSI]

When you have the pump running it keeps the water mixed. It will get a lot hotter at the top with it off.

If you want to run it that way I would drop the water temperature when it is warmer outside. Also going to a 5 degree differential might be better with the pump off.

I would try leaving the pump running though and set the turn on to 155 or 160 and off at 180. That should make it cycle a lot less.

[husky 555]

Makes sense RSI.  Thanks for the suggestion.

[swede]

I agree with RSI about lowering your temp.  On our Shaver the thermostat is set to turn off at 160...plenty hot to easily heat the house and dhw through the stock coil even in the cold of winter.