I just bought a new, [to me], very small one bedroom home which was
built in 1956. The 80,000 [overkill], BTU nat gas furnace was said
to be overkill by my home inspector, probably 30 years old, and
probably won't last another year. He said that a new hi-efficiency
40K BTU furnace would do for this size home. When I asked about
incorporating central air, he said the electric service coming into
the home wouldn't handle it. I only have 60amp coming into the home
from the street, w/100amp breaker box. As you might see, I have a
couple of problems that I want to fix as efficiently and
inexpensively as possible. Where should I go from here? Will 100amp
be enough? How much could I expect to spend to have this work done,
including upgrading the elec service to the home and purchase and
install of his recommended furnace w/or without central air?
You need a pro to do a load calculation in writing as that is the only
way to know what size unit you realy need 40k btu may be oversize or to
small when the numbers are run. What size is the house, location,
insulation, and do you plan on upgrading in the future. I made a
mistake by insulating and new windows after my heat and AC was instaled,
so even though I downsized 40% im still oversized and humid in summer
and overheating in winter. 60a incomming could handle a small AC as long
as you know your loads and what else is used. I can run an 1800 sq ft
house on a 1000w and AC with 30amps. All new apliances and flourescent
lights can reduce your load dramitacly , 75% less than what was normal
of a few years ago. There are more electricly efficient furnaces and AC
units avalaible today. It is all in how you plan your loads and how many
people live there. My new furnace , frige, tv and several rooms of
lights pull 700 watts. The days of ever increasing services can easily
be avoided by shopping by kwh usage. You need a few pros out and a
written load calculation. Do your own energy audit and learn, a clamp on
amp meter and Kill-A-Watt will do it.
If you pay to change your elect service, change it
to something decent 150A+
By the time you pull permit, pay for inspection,
new breaker box, new service wire difference in
cost will be minimal.
HVAC contractors in your area for few quotes on
both furnace and A/C
You are right, you have several issues.
As for the furnace, I suggest you start by contacting a local HVAC
professional. They, assuming they are worthy of the name professional, will
take some measurements plug the results into a formula and come up with the
correct size for your heating and A/C needs. They will also take a look at
the distribution system and make recommendations there as well.
At that time they can offer you suggestions for A/C or not at this time
and tell you the differences in cost now and later. They can tell you what
will be needed for the A/C so you will then have the information that will
be needed for knowing what you will need when you upgrade your electrical.
I am going to guess you will want to go to at least 150 amp. The difference
in cost is usually very little.
Depending on local condition, cost and available choice of fuel, you may
be a good candidate for a heat pump.
You start with the professional as you should use them to help you pick
the proper equipment. No good professional will select poor equipment to
install. They know what works and what does not. They know what is locally
available and supported (parts availability) and what handles the local
I suggest you ask around neighbors, friends and family for
100A is normal for most residential homes in the US and has been for a number of
years. Some larger homes have 150A or even 200A service, but thats unusual.
You really need to get 3 or 4 quotes from reputable electricians in your area.
Variations in regional codes, labor rates and materials will make any numbers
you get on usenet meaningless.
You might also call your electric provider and ask what a service upgrade will
cost, but they are likely to refer you to a licensed electrician anyway.
The first house I owned, built in 1978 or so, had 200 amp service and
electric heaters in every room. They were permanently wall mounted and had
thermostats by the door to the room.
The house I currently live in has 150 amp service and has had gas forced air
heat since it was built in 1973. The AC was added about 1978.
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