96Mustang460cid
10-01-2009, 09:53 PM
This is my first post. I've spent about a week reading on here and have already learned a lot! I will try to keep this post as short as possible while providing the pertinent information. Let me know if you need additional data...
Bought a home, moved in to find high utility bill in winter (winter = $300+/month; summer = $140/month). I called the electric company thinking I had a problem...???
Among other things, the electric company done a model J calculation (Atleast, I think that's what it is):
Indoor winter design temp = 71*F
Outdoor winter design temp = 0*F
Indoor summer design temp = 76*F
Outdoor summer design temp = 100*F
Heating load = 48,518 BTU/hr
Cooling load = 25,067 BTU/hr
I live in a small town and called 'the' local HVAC company. He came and looked at the old setup (3 ton A/C and 120 amp breaker on the furnace). He called today with pricing and recommendations: 4 ton a/c and ???ton furnace. He said the rule of thumb for the furnace is the double the tonnage of the a/c. I asked if he thought a model J would be useful so we weren't guessing. He had never heard of a model J and thought I meant a model D.
Yes, I see the red flags, but this is small town life :).
The current system keeps the house comfortable with trouble-free operation. I am concerned about the efficiency and age/remaining life of the system. So, I am trying to decide if I'm better off replacing it now so I have the time to make a good purchasing decision and work with the local contractors to maximize the quality of work/equipment I receive or wait for it to blow up and replace it ASAP.
Since I expect to move within ~3 years, I don't think a high efficiency unit is worth the $$$ (correct me if I'm wrong).
Questions:
1) Do you have any recommendations on how I can best work with my local HVAC company to maximize product and installation quality? From the conversation we had this afternoon, I believe he lacks a fundamental understanding of HVAC sizing principles. I don't think it's intentional...he's a victim of small town life himself... ;)
2) 2.5 ton a/c & 4.5 ton furnace: is it normally a problem mismatching the sizing like this? He implied that a two speed compressor would be required to get this...yet, his rule of thumb said that: furnace tonnage = 2 x a/c tonnage.
3) I have found that this is a common problem: Being an inquisitive person, I learn about things, but I don't have enough experience (nor the inclination) to actually do the work. So, I can ask the 'right' questions and speak the beginning technical language, but I don't know if the install is actually done correctly... rhetorical ---> but do you have any suggestions?
Let me know if you need anything else. I live in SW Oklahoma.
Have a good day!
Michael
Bought a home, moved in to find high utility bill in winter (winter = $300+/month; summer = $140/month). I called the electric company thinking I had a problem...???
Among other things, the electric company done a model J calculation (Atleast, I think that's what it is):
Indoor winter design temp = 71*F
Outdoor winter design temp = 0*F
Indoor summer design temp = 76*F
Outdoor summer design temp = 100*F
Heating load = 48,518 BTU/hr
Cooling load = 25,067 BTU/hr
I live in a small town and called 'the' local HVAC company. He came and looked at the old setup (3 ton A/C and 120 amp breaker on the furnace). He called today with pricing and recommendations: 4 ton a/c and ???ton furnace. He said the rule of thumb for the furnace is the double the tonnage of the a/c. I asked if he thought a model J would be useful so we weren't guessing. He had never heard of a model J and thought I meant a model D.
Yes, I see the red flags, but this is small town life :).
The current system keeps the house comfortable with trouble-free operation. I am concerned about the efficiency and age/remaining life of the system. So, I am trying to decide if I'm better off replacing it now so I have the time to make a good purchasing decision and work with the local contractors to maximize the quality of work/equipment I receive or wait for it to blow up and replace it ASAP.
Since I expect to move within ~3 years, I don't think a high efficiency unit is worth the $$$ (correct me if I'm wrong).
Questions:
1) Do you have any recommendations on how I can best work with my local HVAC company to maximize product and installation quality? From the conversation we had this afternoon, I believe he lacks a fundamental understanding of HVAC sizing principles. I don't think it's intentional...he's a victim of small town life himself... ;)
2) 2.5 ton a/c & 4.5 ton furnace: is it normally a problem mismatching the sizing like this? He implied that a two speed compressor would be required to get this...yet, his rule of thumb said that: furnace tonnage = 2 x a/c tonnage.
3) I have found that this is a common problem: Being an inquisitive person, I learn about things, but I don't have enough experience (nor the inclination) to actually do the work. So, I can ask the 'right' questions and speak the beginning technical language, but I don't know if the install is actually done correctly... rhetorical ---> but do you have any suggestions?
Let me know if you need anything else. I live in SW Oklahoma.
Have a good day!
Michael