Joined on April 16, 2013
Last Post on March 11, 2014
@ January 30, 2014 7:06 PM in Been away awhile....Anyway, Furnace Help NeededThe integrated furnace control compares the values sent to it by the pressure switch and the pressure sensor. If these values are not the same, the IFC will lock out with a 3-flash. You will need a manometer and a DC volt meter to see if these two components are within the tolerances listed in the IOM. Some causes could be poor connections, faulty wiring, or a failed pressure transducer. It obviously isn't the pressure switch if the issue remains after changing it. Check the PS wiring, the inducer wiring, the PS tubing for leaks or cracks. Also examine your vent system for restrictions (termination kit must match the IOM; 1/4"/ft. slope back toward the furnace; no sags or dips). Make sure the vent system TEL is within tolerances for your pipe size.
A good method for checking wiring is to use your ohm scale (NOT the idiot buzzer). Since the hot and neutral wires are the same gauge, they should register the same ohm value. If one is 3 ohms and the other is 1 ohm, you have a broken wire or loose connection at the molex plug. This logic can be used on all wiring.
@ December 31, 2013 10:31 AM in manometerFiguring out design methods is a non-issue, so don't worry about that. This is all about pressure, and the ability of the blower you have to deliver that pressure against the resistances (pressure drops) in the system. This brings out another fallacy of direct-reading a calculator. The calculator gives you a friction rate, which is the total pressure from blower inlet to outlet. You can't confuse this with a pressure drop, which can occur at any point in the system, and your duct calculator doesn't know what pressure drops you have. For example: if you have a blower that delivers 800 CFM at .55 IWC and you have a 100' duct sized accordingly, you're going to get that 800 CFM. If you add a coil with a pressure drop of .25 IWC, your FR has gone down to .30 IWC. With that same duct, how could you possibly get 800 CFM? Yet every day, you have people telling you this doesn't happen, because they've "been doing this for 25-years and never had a problem." OK, I believe you, and I'll bet you put in a Taco 007 in every two-storey house because "it should work."
@ December 31, 2013 9:50 AM in manometerIt's certainly not you, so don't beat up yourself. It's an industry problem brought on by those lacking understanding of air principles teaching us their lack of understanding. In the 8 x12 duct situation, there are ONLY two situations in which that duct will produce that CFM at that pressure: (1) the duct is exactly the equivalent of 100 feet, and; you have a blower that will PRODUCE .10 IWC of pressure.
It's the same scenario with that stupid 400 CFM/ton thing. They only tell you that to keep you out of trouble. Reading a duct calculator directly and 400 CFM/ton may work; it's just not the right thing to do. High static pressures nationally prove that. Wonder how 400 CFM came about? If you look at studies based upon years of research, and you look at all of the CFM per ton amounts that those jobs should have had and average them, you come up with 400. Does a customer deserve average? They are certainly getting it because over half of the duct systems nationally are underperforming.
Believe me, doing it the right way doesn't take that much more time than using some ridiculous formula someone invented based on averages or rules of thumb. And you give customers the comfort and economy they want, need, and flat out deserve.
@ December 30, 2013 6:57 PM in manometerPaul's original comments were related to an existing system, or at least I assumed as much, since he mentioned troubleshooting. In this case, the procedure is to establish the ESP (external static pressure) from the blower inlet to outlet. This encompasses everything in between; ducts, fittings, registers, grilles, filter, coil, dampers, etc. You then break down the total as to how much pressure is in the SA and the RA so you can see where the problem lies. It's usually easier to relieve pressure on the return side than the supply since the ducts are generally more exposed. Then you determine the pressure drops of the coil and filter and subtract them from the ESP to give you the duct pressure that the blower is trying to overcome. I gave Paul some early warning signals due to the manufacturers rating their blowers at .50 IWC, thinking that amount should be enough pressure for a good duct system and external accessories. However, the national average ESP is a whopping .82! At .90 IWC, the blower is cooked! This means the average duct system is performing at about 57% of its capacity, so you can be a real hero fixing comfort problems with a small effort at overcoming that "I design my ducts at point one" crap.
@ December 30, 2013 9:32 AM in manometerThere is an easy way to do this, yet the discussion is too involved for the space we have on this platform. Contact me anytime. In short, you determine your system total pressure by readings directly at the blower inlet and outlet. Then you determine the pressure drops across all external components; evaporator coil, filter, dampers, etc. subtracting the pressure drops from the total pressure leaves you with what the blower "sees" in the duct system. The "early warning system" is if either your supply pressure or return pressure are at .20 IWC or above, or your duct system pressure is at .30 IWC or above.
Interestingly enough, it is these very principles that will show you that someone who looks at a duct calculator and tells you that an 8x12 duct at .10 IWC moves 480 CFM doesn't have a clue about air flow.
@ December 24, 2013 12:20 PM in aire-flo gas furnace not reaching target temp, i have flash codeYou have presented two distinct issues: open limit and roll-out switch. Regarding the limit, if the filter was formerly plugged and the limit continues to open, the blower assembly or the indoor coil (if you have air conditioning) may be full of dirt, or you could have a duct system issue. The roll-out has a very specific job to do, as it's name suggests, which could be related to gas pressure or lack of combustion air.
@ December 22, 2013 12:50 PM in Its been getting cold outShow me an IOM that recommends a charging jacket, blanket, newspaper, etc. that isn't 20 years old. Convince me that a "band aid" that blocks air flow is what your maker recommends. Prove to me that weighing in, which is what your manufacturer wants in low ambient temperatures, is not the most accurate, or all packaged units would not come pre-charged. Sub cooling remains the same as long as the tubing length is within tolerances and you've added the proper additional charge.
@ December 20, 2013 1:36 PM in Its been getting cold outThe ONLY way is to weigh in the charge. For example, the outdoor section of a residential split system is stamped 6 lbs./5oz. of refrigerant. This means that exact amount is adequate for the outdoor coil, the smallest AHRI rated indoor coil for that unit, and 15' of tubing. If you have a larger coil or longer tube set you need to add "x" additional refrigerant. The additional charge amount is found in the IOM manual or make a call to the distributor's technical department for help. If you do the proper weigh-in, provided your air flow is within factory tolerances, you will be close enough to not have to worry about the unit's performance. When the ambient rises to a temperature that allows customary charging, use the chart inside the OD unit for proper temperatures and pressures. And, as always, check your air flow, superheat, and sub cooling.
@ December 20, 2013 1:09 PM in low humidityYou do not need heat in your air handler to provide a higher humidity level. However, if you're concerned about this, here are a couple of thoughts: when the AH runs, it will circulate the room temperature air provided by your BBs. If you are concerned about the possibility of residual moisture in the ducts, try a thermostat with a "smart" fan option, which will circulate air "x" minutes per hour. The second thought would be a steam humidifier, yet be very careful about sizing it correctly. Steam is not as forgiving as are the by-pass or fan powered units.
@ December 15, 2013 4:48 PM in New forced heat N.G. furnaceLet me know if I can help with loads.
@ December 15, 2013 2:50 PM in New forced heat N.G. furnaceFrom 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 furnaceAnd 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?
@ November 24, 2013 12:28 PM in 80% gas furnaceTry 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.
@ November 24, 2013 12:14 PM in Pulsating liquid line on shut downI 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.
@ 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!
@ 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.
@ 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.
@ August 5, 2013 1:53 PM in Oil vs natural gasNG: $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.
@ August 2, 2013 8:47 AM in high head pressuresMy 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.
@ July 31, 2013 8:44 AM in Leak sealGo 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 capacityAt 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.