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Phil, Mechanical Engineer
Category: HVAC
Satisfied Customers: 6022
Experience:  Retired HVAC/ Electrical & Boiler contractor. Industrial
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I have a pte-110. I cant get the load satisfied on coldest

Customer Question

I have a pte-110. I cant get the load satisfied on coldest days. One zone has large pipes and CI rads (gravity 2-pipe) and I'm looking for maybe raising the set point from 162, or bypassing the reset, or some other solution before ripping out the steel pipes and running 3/4 pex to the CI zone
JA: How long has this been going on? And how severe is the problem?
Customer: Installed last fall (my 2nd such unit, the other performs excellent). Customer not pleased
JA: Do you plan on doing the work yourself?
Customer: yes
JA: Anything else we should know to help you best?
Customer: I just need to satisfy the call on colder days. I tried messing with the curve, I put a larger circ on CI zone, I installed a valve at the injection loop. Really don't have the time to replace all that large pipe with 3/4 pex, and not sure that will solve the issue...
Submitted: 9 months ago.
Category: HVAC
Expert:  Rick replied 9 months ago.

Welcome to Just Answer, my name is ***** ***** I will do my best to help you with your issue. If my initial response doesn’t answer your question then let me know and we can continue our conversation.

The problem is that there is too much water volume in the gravity zone. New low mass condensing boilers are not compatible with old gravity systems. Even with a new cast iron boiler we up size the boiler at least 2 sizes larger than heat loss demand would indicate in order to handle the extra water volume in a gravity system.

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