Hot Water Heater Question

A friend of mine, whom I doing my last mock inspection for (yes I’m a newbe) is installing a new HWH and asked if the supply can be from a hot water line. This is for a secondary hot water supply, the primary is a oil fired furnace. I’m not sure why he would want to do this, but I would like to give him an intelligent answer.

Is it a boiler not a furnace? Does the oil boiler have a separate zone for the domestic hot water?

It sounds like the new one may just be for storage?

Typically, for 2 water heaters, this applies:…riesPiping.pdf



Any idea why the first water heater will condensate (SP?) more than usual?

Seems the same to me. Condensation is from cold water. All water heaters get cold water dumped in them?!

In series, the first one get cold water and the second gets warm or hot water is what I was thinking.

I guess they are reasoning why the first in series heater fails sooner than the second.

The second does not get condensation because it always gets hot water (if they are close enough to each other).

Not that the first one fails sooner than normally expected. The second on just lasts longer.


Refer him back to the manufacturers of the equipment in question. Who knows what kind of issues can be involved with doing what this guy wants to do? The manufacturers might also have equipment that is better suited to what he wants to accomplish. Even if this person is a friend, that friendship might end pretty quick if something goes wrong. Know your limits.

To clarify - it is an oil fired boiler and I do believe the second HWH will be used for the bathrooms. It will be located approx. 30’ from the main boiler.

Thank you for the responses - I think it will be best to have him verify with the manufacturer.

yes, that is the way you connect the “point of use” tanks that you see under sinks etc.