Since there appears to be some confusion on this unit, this post is
meant to clairify:

Aqua Therm is made by First Company, and utilizes a Hot Water Coil fed
from the dwellings hot water heater. This hot water coil is not
"radiant" heat as one respondant hypothicated, but rather incorporated
in a Forced Air Unit. A blower forces air through the hot water coil
and out the supply ducting. A "Taco" pump pumps the water through.
The SAME water that is used for the buildings hot water is used for
space heating. The hot water from the hot water heater is fed through
he coil, and the return feeds back into the cold water supply inlet to
the hot water heater. Obviously there are check valves.

In answer to another posters musings, there is no problem with the
heated water being used double duty for Space Heating and for potable
water supply. Copper pipe is used for building plumbing, and for coil
heating applications. Absolutely nothing harmful is introduced to the
water, it is simply circulating through more pipe. That is all. In an
extremely simplistic example, it is as if we were simply placing a fan
across the hot water pipe coming off David's hot water heater and
making use of its heat to help heat the space. There in lies the rub,
and David's problem: If we force air over the hot pipe, the pipe will
give up some of its heat. The water then is not as hot as it was.

In answer to David's question, there is not a lot he can do. When the
heating unit is in operation, hot water from the water heater is
circulated though the coil. Air is forced over the coil, taking heat
from the water which is then returned to the water heater. The water
heater must cycle to re-heat the water.

David can increase the temperature of his hot water heater. In doing
so, he will increase the heat output of the heater (Aquatherm), and
gain some residual benefit of an increase in the buildings hot water.
He might consider putting scald guards at his fixtures if he ups the
temp too much. This will naturally raise David's utility bills, as the
Heater will run longer.

He can also consider changing the water heater to a larger unit, and
one with the greatest recovery rate he can afford.

Since your hot water is being circulated in a coilIn article
, David
wrote:

Hello, I have an AquaTherm furnace connected with a 40 gallon hot
water heater. When the furnace is on and using the hot water heater,
I get either no or only luke warm water in the house. Does anyone
have any idea what the problem is? Is my hot water heater going, or
is there any adjustment that I can make? Thanks in advance!