74' Heater Core Pre-installation Test

[Robert S.]

I have a 74' with AC and am replacing the heater core. I pressure tested the new core with about 25 psi air by putting the new core under water. The new core is now installed in the heater box and before the box assembly goes back in I want to do another leak check as I know I put some stress on the tubes as part of putting the heater core into the box. The box assembly is such a bear to remove/install I do not want to pull it out again once it is in place.

I am think about attaching hoses to the tubes, plugging one hose end with a wooden dowel and applying house water pressure to the other hose and looking for water leaks out of the heater box. I am trying to find out from the water company the approximate water presssure at my house.
Question: Has anyone done this and does anyone see any danger of doing damage to the heater core as the house water pressure may be higher than what the heater core sees once installed?

[Dick W.]

Re: 74' Heater Core Pre-installation Test

DO NOT use more than 15 psi to test the core. They are designed to operate at this pressure, max. Any more pressure that this and you could stress the core to the point of failure.

[Michael W.]

Re: 74' Heater Core Pre-installation Test

Some houses have up to 100 psi water pressure, even low performance well pumps usually give you 30-35 psi.

Don't risk it like Dicky said.

[Larry M.]

Re: 74' Heater Core Pre-installation Test

Robert:

Disconnect the power to your air compressor and drop the tank pressure down to about 20 psig. Connect a hose from the compressor to the lower heater core connection. Fill the core with water from the top connection and then cap it when full of water and all the air is out. Now open the hose connection from your compressor.

If you have a leak, you will see the water trail and the pressure on the compressor tank will slowly fall. No leaks and no pressure loss = success.

Larry