"Jason" wrote in message
.com...
"Toller" wrote in message
...

"Jason" wrote in message
. com...
I have a 35 year old 100 amp service. I had my old furnance and AC
replaced with a geothermel unit about a year ago. When they did the
install they used all of the remaining free slots for new breakers. The
issue is when the unit comes on the lights dim for a second. Will
upgrading to a 200 amp service prevent the lights from dimming?

Impossible to say.
I don't know anything about geothermal units, but they couldn't possibly
take anywhere near 100a even at startup.
If it dims your lights and electric stove and electric water heater are
on, then yes, a larger service will likely help you. Or try not to run so
many heavier users at once.
If it dims your lights when nothing is on but a few lights, then no, it
probably won't help; the problem lies elsewhere.
Also, it would be nice to know current your geothermal unit draws.

In AC mode it is supposed to take between 25-30 amps. 1 20amp circuit is
for the circulation pump. 1 60 amp circuit is for the unit itself, the
blower, and the electric backup heater. The lights only dim with the unit
turns on. After a second the lights return to normal. It just gets a
little annoying when you are reading a book and the lights dims.



I do not have an electric water heater. I don't have any really heavy
users of electricity. I typically only use my PC, frig, TV, sat receiver,
microwave, and a few lights. They are all on different circuits and only
sometimes used all at the same time. I really don't use a lot of
electricity so I don't what is causing the lights to dim. I blame the
geothermal unit because it happens when the unit turns on. Any
suggestions as to what it could be?

Can you get ahold of an ampmeter? If you measure how many amps are being
used on each leg before and during startup, you will have an idea where to
go.

It is hard to know otherwise. 30a is a lot of current on a 100a service,
but not if nothing else is using current. But it might have much higher
startup current; no way to know without testing or asking the manufacturer.
My refrigerator uses 16a to start, but only 1a to run. On the other hand,
your backup heater probably uses the same to startup as to run.