Viessman Boiler questions

Old 03-04-15, 07:47 PM
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Join Date: Oct 2011
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Viessman Boiler questions

I have inherited a Viessman vitogas 100 boiler. With the extreme cold I had some pipes freeze in the basement. I have repaired the leaks and refiled the system and bled the air. What is the optimum water pressure I should be keeping the system at? I did not notice what it was before the system failed and currently have it at 25 psi.

Second, in order to prevent this in the future is there a way to keep the pump running 24 hours a day when the temperatures get too low? I live in a raised bungalow with a well insulated upper level where the thermostat is located so the furnace runs to keep that level warm. The basement however is a full concrete floor and walls, so it is always cold to start with. I would like to be able to set the pump to keep running in the future if the temperatures are forecast to go too low, whether the boiler is firing or not.

Thanks D.
Old 03-05-15, 06:20 AM
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12 - 15 psi cold is the norm for a two story home, boiler in basement. Where did the pipe freeze, basement or in an exterior wall? If you have access to the pipes, wrap them with foam insulation.
Old 03-05-15, 04:29 PM
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Is your DHW made with the Combie unit ? Is the boiler piped with there low loss header? You could power the circulator using a thermostat and a relay that would power up the pump at a selected temperature.

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