Security Seal Facebook Twitter GooglePlus Pinterest Newsletter Sign-up
The Wall


Joined on April 16, 2013

Last Post on March 25, 2014

Contact User

Recent Posts

« 1 2 3 4 5 6 »

HE Furnaces

@ December 15, 2013 2:50 PM in New forced heat N.G. furnace

From your words "most efficient" I assume you refer to an AFUE beyond 90%, in which you will no longer be using your chimney. However, if you are orphaning a water heater by removing the furnace, you will need a liner appropriately sized for the water heater (see the GAMA tables for sizing). If your water heater is in a separate chimney and no other fuel-burning appliances use the chimney from which the furnace came, you can use it as a chase to terminate your new furnace, provided you follow your maker's venting instructions and you insulate the intake/exhaust pipes appropriately. Or, abandon it entirely and use the sidewall option.

As far as the efficiency of units is concerned, each manufacturer publishes efficiencies which vary by maker and BTUH. Run a load calculation to determine the correct output and air flow needed for your home, then compare efficiencies. Don't micro-manage AFUE ratings; the difference between 96% and 97% is hard to justify. More important is choosing a BTUH output and a blower that will deliver that output against the pressure losses of your duct system. From there, find a convenient distributor who will be there for you when you need parts or technical help.


@ November 24, 2013 12:52 PM in 80% gas furnace

And to key off Bob, even though the code says you can go up in sizing, that doesn't mean you should or that it is a good idea. A result of getting to 80% AFUE means a flue temperature that easily is 150 degrees cooler than an old wheezer. Lower flue gas temperature, bigger pipe could mean condensation. Ever wonder why you see so many 80s with chalk and rust on the connectors?

Furnace Venting

@ November 24, 2013 12:28 PM in 80% gas furnace

Try to get as much straight pipe as you can from the furnace to your 1st elbow , remembering that your vent connector must have a lateral rise of at least a 1/4" per foot.

Can you terminate your connector into a 6" common vent? Yes. Should you? Perhaps not. I'm not familiar with a "Type A" chimney,, so I would check the GAMA tables for single appliance verification of sizing based upon the parameters in the table for your common vent, BTUH input, lateral length, etc.

Pulsating LL

@ November 24, 2013 12:14 PM in Pulsating liquid line on shut down

I would make certain you don't have a stuck or leaking check valve or reversing valve. Also, make sure your TXV's feeler bulb is at either the 10 o'clock or the 2 o'clock position on the suction line.

Help Needed!

@ November 22, 2013 12:23 PM in Help Needed!

Looking for two Smith 8S6 boilers. If anyone knows of any in the MA, CT, DE, NY, NJ area your assistance will be deeply appreciated!

Two Months

@ September 2, 2013 9:30 AM in Electric Heat???

Got it now. For some reason, I thought the family friend was the landlord, not the tenant. My error. The easiest solution: Macy's is having their annual sweater sale this week.


@ September 2, 2013 9:01 AM in Electric Heat???

How much does 100,000 BTUH of electric heat cost? If you pay, for example, $0.17 per kWh, then 100,000 BTUH of electric resistance costs $4.98. A heat pump with a COP of 3.5 costs $1.42 for the same 100,000 BTUH.

Electric Heat

@ August 30, 2013 4:16 PM in Electric Heat???

You would be well-served to consider a mini-split heat pump for your cottage, especially one with a high HSPF. For example, a mini with an HSPF of 9.5 would transfer 2.78 times the amount of heat that it would use in electricity, a 10.2 would transfer 2.98, and you have air conditioning too. And, as suggested by the others, make the load smaller by insulation and other weather sealing measures. These measures should absolutely be done before you do your heat loss/gain calculations, so you can take advantage of the benefits of smaller capacities.

How Much Does 100,000 BTUH Cost?

@ August 5, 2013 1:53 PM in Oil vs natural gas

NG: $0.00 per 1,000 ft3 divided by 10, unless your utility prices it in therms. A therm is 100,000 BTUH, so there would be no division.
LP: $0.00 per gallon times a factor of 1.087
Oil: $0.00 per gallon times a factor of .72
Electricity: $0.00 per kiloWatt times a factor of 29.3

Since we are talking about the same amount of heat (100,000 BTUH), this makes fuel cost comparisons easy to understand and appreciate for both technician and customer.

Hot OD Units

@ August 2, 2013 8:47 AM in high head pressures

My best guess at the moment, since your SH is within reason, is that you have a relatively small condensing coil with not much surface area. Since about 85% of the coil should be condensing, the superheated vapor (about 15%) would have to be quite high to allow enough time for the ambient air to convert it to a full column of liquid (about 5%). And, some of the older coils did not have multiple passes either. With this in mind, one could assume the hot gas going into the coil could easily be 225 degrees or more; higher with a hotter day. As an experiment, check the hot gas line temperature before the pass manifold and then check each pass that enters the coil and compare it to units that are the same vintage yet not frying like the Goodman.

Leak Detection

@ July 31, 2013 8:44 AM in Leak seal

Go with RJ; nitro and tracer refrigerant. Only two things belong inside your system, period: refrigerant and oil.


@ July 24, 2013 4:48 PM in zerol ice reducing system capacity

At an ambient of 87 degrees and an IDB of 81, you have a huge load on the system, leading to longer run time and high SH. Also note that your latent load is massive (71 degrees WB), so it is extremely difficult for your machine to neutralize that load with only a 14 degree TD. With a 15' lineset, your factory refrigerant charge should be dead on; perhaps off a few ounces if you have a large evaporator. It sounds as if an airflow calculation is in order.

The Wall

@ July 24, 2013 4:17 PM in I know now why I quite coming to the wall

It is my firm belief that 4/3 of us are highly educated.

Oil Foaming

@ June 23, 2013 9:02 AM in why would Compressor vibrate?

Again, check pressures and amp draw against nameplate. Sounds as if you're running hot has anyone checked, really checked, the condenser coil?


@ June 21, 2013 5:56 PM in why would Compressor vibrate?

If this is a start-up and you have a scroll compressor, it might be running in reverse. If this is the case, switch around the power legs at the disconnect until it quiets down and your pressures look normal, or if you have a phase monitor, the LED will be green when it is happy.

Bearing Check

@ June 21, 2013 5:45 PM in why would Compressor vibrate?

Attach your gauges to see their readings as compared to the factory charts. Under operation, measure the compressor amps on the COMMON lead. Compare your amps to the nameplate. If your vibration is not a broken mounting spring and your amp reading is 15% or more above the nameplate, that would certainly indicate damaged bearings.


@ June 21, 2013 5:36 PM in why would Compressor vibrate?

Do you have a hermetic (sealed) compressor, or a semi-hermetic (looks like a small car engine)?


@ June 21, 2013 11:58 AM in why would Compressor vibrate?

Some manufacturers put large compressors on springs. If this is your case, after hundreds of hours of operation, a spring or springs can break, throwing the compressor off-balance. Kits are available for replacement.


@ June 15, 2013 10:25 AM in High subcool

Sorry I didn't respond last night. I was charging myself to a full shot glass.

With the new coils so tall you need a bucket truck to get to the compressor, as long as the manufacturer doesn't object, putting the drier at the service valve sure makes it easier to install, read temperature and pressure across the body, and change the core if needed. I'm still at a loss as to why Rick's units have them, yet they are there, and the PDs are out of line on a couple of them at least.

SLD Placement

@ June 14, 2013 6:24 PM in High subcool

For the same reasons you place an air filter as close as possible to the blower inlet. Plus, the makers of the driers recommend it for best results.

Mystery Units

@ June 14, 2013 2:56 PM in High subcool

Look at Unit 3. Your head pressure converted to temperature and the ambient are dead on target! I'm going for air flow or overcharge. Send us your ESP and the CFM at that figure from your blower performance chart in the IOM manual that came with your indoor unit. Along with the load test, we will nail this thing.

High SC

@ June 14, 2013 2:47 PM in High subcool

First lets review the test. As I mentioned earlier, condensers below ambient shouldn't be. Hook up your head pressure gauge and turn the system off. Place a quality thermometer at least 6" from the coil, but not in direct sunlight. After at least 20 minutes, your head pressure converted to temperature and the ambient should be the same. If still lower I am concerned that your ambient and the inside temperature are too close, causing liquid stacking in the outdoor unit. Only a load will tell at this point, other than recovering some refrigerant, which I'm sure you would rather not do right now. It's 72 outside, yet in the 50's and low 60's inside, so your system is loafing. That being said, your SC would still be correct with the correct charge. Since you have sight glasses installed and there seems to be a tremendous temptation to charge to a clear glass for reasons I'll never understand, I'm betting on too much refrigerant. Turn the 'stat to "pizza oven" and see what happens to your SC. We'll save the SLD mystery for later.
« 1 2 3 4 5 6 »