Fact or Fiction

[Cindy here]

Howdy,
Sorry to bother you but I have a few questions please. We purchased a new hvac heat pump central system and I did a lot of research. The current one was a 3 ton and the people that we select after I did lots of research on all 4 companies told me my home should have a 3.5 ton system. The 16seer unit didn't come in 3.5 ton so we were talked into a 4ton.

Anyway, we installed the system but the heat was worse than what we had, they came out and took out some freon. The energy bills were great, however since then it has gone downhill with this system. In the winter it really doesn't work and the HVAC guy is out at least 2 times a year because we have no heat and the unit runs on high all the time, and the energy bills are through the roof. We called a few other folks and they cant or wont work on the unit because it is a hybrid unit, but are willing to sell me a new one.

Moving forward - Yesterday I called out a different company because now we are having trouble with air. The unit cant support 78 degrees. It will run on low then go to high. Back and forth. This guy said we need new ducts at a nice cost of over $. our home is only 1684 sq feet. Do you think this is the trouble or am I getting the run around again? Why didn’t the original HVAC guy tell us we needed new ducts. I don’t know who to believe.

Please let me know,
Cynthia

[Southern Mech]

Sounds legit on the ductwork, going from 3 to now 4 tons of air. Provided it was even sized properly for the original system. Instead of spending the money on ductwork, I would reccomend your new company to perform a manual j load calculation and see exactly what your home needs

[Cindy here]

Thank you for your reply. What is a manual j load calculation?

The unit is only 4 1/2 years old and I can not afford to buy another unit. This one already costed $, not including install, haul away and all the repair calls to get the thing 1/2 working. I could maybe get about $ together for new ducts and a reconfigure of the box (cant remember name) where all the ducts feed from. But now I am so concerned because what if this does not solve the problem? A simple new replacement unit is becoming a nightmare and a money pit. i.e. electric bills, unit cost, service calls, install, haul away, and now new ducts. I will be upwards to $ when all of this is done. We already own a money pit and I dont want to keep spending money on HVAC unit. What is the life span of a HVAC unit anyway. 10 years? Do I need to start saving for another one now? oh my gosh, i am stressing out.

[dandyme]

there's a AOP forum this belongs in

[Cindy here]

Sorry I thought I was on the residental HVAC forum. It looks like you moved it and I thank you.

[Shophound]

Has there ever been a time when both the heating and cooling worked properly on this system?

[Cindy here]

Hi Shophound,
Nope. We replaced the old unit which was undersized for the house in Jan 2008. A week later we had getting heat. It was 59 degrees in the house on high. They came out and took out the freon. It got a little warmer. But to be honest for heat you have to pump it up in the day so it can be 62-65 in the evening and we have modified how we wear our clothes. In the summer they had to come back to add freon. It has been a complete circle this whole time. Then it was thought it was the thermostat, but all they did was hit reset. The codes on the unit and there were many, were taken away for research and they came back hit the reset and either added or removed freon. Or could not find out what the trouble is. I had multiple HVAC people come out saying they can work on the machine but when they get here they cant figure it out either and try and sell me a new one. This year of course is a bit different because it is hotter. Of course this time I when I called someone I asked for people who had certification period. I didn't go back to the orginal hvac guy. I was done with them last year with the whole hit reset and leave on both the unit and the thermostat. When this new guy came out he went in the attic came out and said. Is your unit doing this, and I said yes and he said you need new ducts because the unit is not able to process the air out to the ducts fast enough and the duts are way too small. But after all this drama, no i should say saga why has no one ever told me we needed larger ducts? Why didn't they tell us this in the beginning? So I dont know if this guy is just giving me another line so he can make a sale or what. Hence the reason I am coming to you.

[Shophound]

What you truly need is a firm foundation to base all other decisions about your system by. And that would be an accurate heat load calculation, known commonly as a "Manual J". From this "stake in the ground", a real pro can then make informed decisions on how much tonnage your house actually needs, both for heating and cooling, and whether your existing ducts are large enough for the calculated tonnage.

Someone somewhere told you your old unit was undersized for the house, but how did they know? Did they run a Manual J and arrive at that decision? Or did they just pull a number out of thin air and say, "Here, this will work". Sounds like the latter is the case. Happens far too much. Based on "I've been doing this HVAC thing since dinosaurs wore wooden underwear". Sounds quaint but it's no substitute for basic HVAC engineering, which anyone in this trade should get familiar with.

Far too often HVAC sizing is driven by upselling pressure, not sound engineering. As for your current system, with a reported history of techs adding and removing refrigerant, that indicates an airflow problem, which might be due to the increase of tonnage from three to four, with no alteration in ductwork. Being this is a heat pump, in winter the system trips on high pressure because it can't move enough air, so they take refrigerant out to compensate. In summer the system can't cool well enough, so they add some back in. This is because on any heat pump, the indoor coil and outdoor coil are not the same size. So if the airflow in winter isn't high enough, the system trips on high pressure. The only way a heat pump can work correctly is if it has enough airflow for both seasons.

[TwincamDave]

If you got receipts for all the repairs,and you should. Get them together and call the factory about this and get them involved.

[catmanacman]

Sounds like you were taken advantage of .hardly ever does house need a larger unit. Usally its the duct system thats undersized then you go add a larger unit and the unit does not work right. What size are type of filters do you have

[wahoo]

First off, you should have been SHOWN a manual "J" figure to prove that you actually needed the larger unit. Now that you've got the unit, you're kinda "stuck" between a rock and hard place especially if ductwork was not increased in size to handle the additional air flow. In a salesman attempt to increase prices thru efficiency, oftentimes the additional work is overlooked at the peril of the homeowner (who does not get the actual efficiency they paid for). Increasing the size of the unit by 33% would demand an actual J computation, along with a thorough evaluation of the ductwork capacity. I'd keep track of everything and also call the factory and ask for their field service rep. to come and look over your problem.

[udarrell]

...This guy said we need new ducts at a nice cost of over $. our home is only 1684 sq feet. Do you think this is the trouble or am I getting the run around again? Why didn’t the original HVAC guy tell us we needed new ducts. I don’t know who to believe.
Please let me know, Cynthia

First, you don't need a 4-Ton system in Sacramento CA for a mere 1684-sf home!
Your home could have had a few low cost things done to it so a 3-Ton system would have cooled it; that's only 561-sf per ton of cooling
Yes, I know what the 2.5% summer design is for Sacramento CA...98-F dry bulb, 70-F wet bulb or, only 26% RH which leaves a lot more sensible capacity to run airflow at 450-cfm per/ton of cooling.

Then the duct system would probably not needed any high cost work, plus the initial cost of equipment would have been less.

A manual J room by room heat-gain calc should have been performed & any work needed to make a 3-Ton system work should have been performed.

I would have evaluated the duct system & airflow &, therefore, would never have sold you a costly 4-Ton system for your home.

It was their unprofessional error, not analyzing the duct system, etc.; I'd try to get them to take the 4-ton back & install a 3-Ton heat pump with the minor things to make sure it does the job to your satisfaction.

[beenthere]

No prices please, thank you.

[beenthere]

The company you chose, had a good salesman at your house. To bad he was probably more interested in his commission then in your comfort and operating cost.

Go out and but a 5 gallon gas container. And everyday go to the gas station and put 6 gallons of gas in it. Probably won't work to well. Your HVAC system is having the same problem.