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Thread: How would you size this job ?
07-16-2008, 09:21 PM #1
How would you size this job ?
Guy calls and says that he wants to get off propane heat. He has a 2 ton AC and a 50K propane furnace.
Over the telephone I suggest a heat pump, we talk about the why's of it all and so forth, and he agrees.
I do the load calcs and come up with 13,200 cooling and 24,350 heating. So the closest I can do is an 18,000 BTU system which give about 18,000 heating as well. New coil, cond, air handler, 7.5KW electric heat.
He and I go over the various numbers (real nice old guy) and talk about it.
The guy says: Well, why not just install a 2 ton? That will give me 24,000 BTU's for heating and I'm happy with the 2 ton AC I have now. And that will have me using the backup heat less and so saving money by running the heat pump more.
So at first I argue and talk about how important it is to have the AC sized correctly and so forth. But after a while - I start to see it his way: The 2 ton HP Will heat his house better and cheaper than the 1.5 ton. And, as he says; he is perfectly happy with the short cycling 2 ton AC.
BTW: He keeps it on 80 degrees - which isn't helping the short cycling any. <g>
I did think again about my two speed heat / one speed cooling idea. <g> Install two speed two ton and have the 24K heating he needs and the 12K cooling as well. But he doesn't want to spend the money for the two speed. Says he won't live to see it pay. He's 90. <g>
So . . . . . what do you all suggest?PHM
07-16-2008, 09:45 PM #2Professional Member
- Join Date
- Mar 2005
- Houston, Texas
Rule # 1. The customer is always right. I know it's not right, you know it's not right. Give the old timer what he wants or someone else will. He's right, no way will he live long enough to see a return on his investment.
07-16-2008, 09:52 PM #3Professional Member*
- Join Date
- Mar 2001
- North Carolina
What is the location used for heat load? design temps?
07-17-2008, 12:58 PM #4
He's in Gloucester County NJ. (exit two in jersey-speak)
I used 70 degrees for heating - (0 - 70) I used 20 degrees for cooling (100-80).PHM
07-17-2008, 01:56 PM #5
On heat pumps, 25% over sizing on cooling load is allowed in Manual J.Contractor locator map
How many times must one fix something before it is fixed?
07-17-2008, 03:08 PM #6
Yes, but -
The cooling load is barely over 13K. The smallest residential system I can buy is 18K. 27% oversized instead of 25% - which is still pretty close. So yes; I am fine with that.
But . . . . the 18K leaves me short on the heating side, the customer knows it, and wants to favor heating.
A few years back I mentioned that his oversized AC (2 ton) would work better if he ran a dehumidifier in the house. So ever since he has had one running non-stop with the AC. It's set to 40% and sitting on a plank over his washing machine. When the washing machine is full - he washes his clothes in the distilled water. <g>
He says that he's happy with that arrangement - so why should be go light on the heating side now? And then have to make up the difference with more expensive electric heating? And plus; not get all the "heat pump savings" that he could get by installing the 2 ton heat pump. Which was my whole 'selling point' to him in the first place - he's using my own logic to justify his position - which make it hard to argue against it effectively. <g>
It seems to fly in the face of my in-grained 'accurate sizing is everything' training, but . . . . I'm really starting to agree with him. <g>
That's why I wanted to bounce some ideas around with you.
07-17-2008, 09:00 PM #7Professional Member
- Join Date
- Nov 2007