The Hotline: 09/03/2007
September 3, 2007
I am trying to find out if head-master-head pressure-mixing valves are the same thing or what the difference is. Does one work on condenser pressure? Receiver pressure? Does one back up in the condenser and one bypass the condenser? How do I tell the difference in the field? Do these valves have three- or two-pipe connections?
From Emerson Climate Technologies
The HeadMaster was the first head pressure control valve to incorporate both receiver pressure control and condenser pressure control into one valve. Before the Headmaster, it was necessary to use two valves to accomplish this; one to flood the condenser and one to divert compressor discharge gas to pressurize the receiver. This method is sometimes referred to as a two-valve flooding system.
The HeadMaster is a three-way or three-ported valve. The three ports are respectively connected to:
• the compressor discharge line;
• the condenser inlet; and
• the receiver inlet or condenser outlet line.
A constant gas pressure charge, which is contained in a dome on top of the valve body, controls the valve’s operation. The compressor discharge gas pressure entering the valve is compared to the dome pressure. If the discharge gas becomes higher than the dome pressure, the valve modulates to increase flow through the condenser while closing the port to the receiver.
If the discharge gas becomes higher than the dome pressure, the valve modulates to increase flow through the condenser while closing the port to the receiver. If the discharge gas pressure is lower than the dome pressure, the valve modulates the condenser port closed while opening up the receiver inlet port. This causes the discharge gas to bypass the condenser and pressurize the receiver while also causing the condenser to flood. This then maintains the head pressure comparable to the dome pressure preventing the head pressure from falling too low.
The term mixing valve is a generic term, although it applies to any valve that has three or more ports and modulates the flow of the fluid, which it controls. The HeadMaster, therefore, falls into this category.
Natural Gas FurnaceQUESTION:
By Gary Christenson
I am a homeowner looking for replacement burners for a vintage Lennox GS10Q3 natural gas furnace. These burners are no longer produced by Lennox, so I’m hoping a shop or warehouse somewhere has some sitting around gathering dust.
The equipment in question has been out of production since they were last built in 1983. You did not give a complete model number or serial number, so we cannot give the exact information for the gas furnace.
About all we can do is list the two burner part numbers. The burner that holds the pilot bracket is a LB-18867CA. The rest of the burners (depending on capacity 4 to 9 burners) would be part number LB-18853C.
We would strongly recommend (due to the age, low efficiency and parts that are no longer available), that the furnace be replaced with a new high-efficient system.
New Heat PumpQUESTION:
From Debbie Caplette
I’m hoping you can help me with my current situation regarding the purchase of a new heat pump. This is my problem: I currently live in a condo and my present heat pump has died. I have chosen to purchase a new heat pump that uses R-410A.
Unfortunately these heat pumps are larger in dimension. Presently my heat pump is in a fenced in area with two other heat pumps. One of the condo owners has upgraded to a Carrier unit using R-410A, and has taken up most of the existing space. I have tried to have the condo association approve enlarging this area (not necessarily having them pay for it).
My argument is that the newer high-efficient unit is larger in dimension regardless of the SEER. The condo president is trying to tell me to buy a heat pump that is smaller and does not use R-410A. So this is where I need help from you.
Are there any articles that I can reference (with recommendations from federal agencies) regarding switching over to R-410A? Why should I have to convert a system when I can purchase one with R-410A to begin with?
I feel that the condo association has to start preparing for the future and make it easier for new purchasers to update their units … not only being more energy efficient but also kinder to the environment.
I don’t know if there is a law or something published that would justify these newer units.
Please help me.
The old heat pump is more than likely 10 SEER or less. This in itself is why the unit is smaller. Higher-efficiency units, regardless of the refrigerant used, require more refrigerant. With more refrigerant, you need more coil surface, and more coil surface equates to a larger unit.
Carrier’s Puron refrigerant (R-410A) is more efficient than R-22. Therefore, when comparing refrigerants and higher efficiency deluxe models, Puron refrigerant units are smaller in size.
Carrier offers residential new construction models that are smaller in size than a deluxe model, but they will have lower sound features.
Also, as we draw closer to the 2010 R-22 phaseout date, the cost of R-22 will increase and cost much more than R-410A refrigerants such as Puron.
You are absolutely justified in your assertions that installing an R-22 unit is not only an exercise in obsolescence but not very enlightened either.
If you have a technical question, fax it to 815-654-7278 or submit it online by visiting The NEWS’ Extra Edition page and clicking on The Hotline link in the left-hand column.
Publication date: 09/03/2007