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On a copper fin boiler like lochinvar or RBI dominator how does the air proving switch measure a differential when one side of the air flow switch sits in the burner compartment and the other side...

How does increasing airflow reduce static pressure?

Interesting could you please expand on that

Much agreed but the partial removal of the filters stops the whistle. My question is does the majority of the air just use that clear unfiltered space say 6x36 since it'll naturally seek path of...

Dont know if "gapping" is the word im looking for but read on. Consider the following; a filter rack with 2 oh say 18X18X1 filters. The return size is pinched down for what ever reason through the...

Hello. Going to be taking boiler ops test soon for MN class 1C, just wondering if anyones taking it and what to expect from the exam. Thanks!

Thats what i figured. Thanks for confirming

What is the resistor between cm and one direction on a 2 position (open/close) 3 wire 24V actuator for? Worked on a system the other day with a 3 wire belimo actuator (TR24-3-US) with a 1000ohm...

Apologies for the confusing title. Replaced a Honeywell Helix style fan switch/limit on an older Lennox furnace yesterday. Nothing unusual about the furnace except the original fan switch had an...

While I agree 100% in this case it was a sunday emergencey call call and given the OT charges and the fact that it was a small ma and pa operation I made my suggestions to the manager to correct said...

Service call this weekend- walk in cooler warm. Compressor short cycling on overload. Found start cap no good- replaced it and pot relay. Noted evap fan not running, checked that out and found it...

thanks for the great responses. Ill try to answer things to clarify- Im using a -5" to +5" mag gage with a high and low port- i assume thats what you mean by dual port. I zerod it outside as a...

Can you use a magnehelic to verify room/bldg pressure? I find that if i light a match and open the door there is a slight draft to the outside so that tells me that im slightly positive- good....

How do you guys set unloaders in comm AC apps with Hot gas. a very reputable source told me with a comp with 1 unloader set for 55 and 65 for 2 1 at 55 and 65 and the other at 65 and 75 (R22). Where...

Actually yes the pot relay was an aftermarket. In this case I replaced all 3 components with OEM parts. If memory serves the contacts on a pot relay are between 2 and 5 and are ... ... N.C (?...

I agree however in this case it was running fine an hour prior to doing my work inside the box. Nice trying to explian that one.

Title a little more dramatic than need be. Went on call other day- dual evap med temp walk in froze up. Made few observations. We just took cust from another company. first off cycle timer not even...

Regardin post 2_I understand the operation and purpopse of having a CPR valve but why do you only see them (mostley) installed on the K-bodys but not the cans of the same capacity?

Couple questions. What is meant by "dynamic system"? also I can understand having saturated liquid in the receiver but isn't the liquid refrigerant subcooled before is drains to it? Also why isn't...

http://www2.dupont.com/Refrigerants/en_US/products/Suva/SuvaMP39.html

hope that works-note the part "recommended lubricants"

Just read on Duponts site that only AB or MO is recommended with MP39. Thought i was ok to run with POE. Wouldn't 134a be a better choice with POE on a smaller system anyway?

Can we open the floor to a bit of discussion on double risers. Also I can see how a trap at the bottom reduses the effective id of the piping for velocity, but cant see how an inverted trap at the...

This is the best explanation Ive ever heard! In fact it was a Trane thing that I was reading that said it wasnt necessary to trap with good piping practice.Thanks

One thing thats never been explained to me was how having an oil trap helps oil return. Is it just to stop it at a certain point? I was doing some studying recentley on piping practices and it said...

Assuming your directing this at me I graduated from 2 year tech 5 years ago and just completed my apprentiship. HVAC/R is quite an extensive trade and I consider schooling a liscense to learn. In my...