I’m going to inspect my first home with a hot water system for heating on a homebuilt in 1922 in a couple of days.
What should I be looking for? I’m a little nervous, although I know the buyer??
Roy Drangstveit
Remember it is just a big tea kettle.
Check expansion tank as you do not find them on HVAC.
Do not bother to look for A/C lines:)
Check burners
Pump for circulation.
Flue
water pipes
Check registers or radiators.
thermostat.
No filter 
Those are the main things I look at.
You could get into checking gauge readings and valves if you are up on it.
If it’s as old as the house, it may not have pumps, the water may just move by convection. Expansion tank may be in the attic. Flue may have a barometric damper.
If you open a bleeder on one of the radiators it may or may not close again. If you screw with the zone valves, they may or may not break off, leak, or never work right again.
You might wanna do a little reading before-hand, they’re not that complex. I’ve been a boiler operator for 15 years, and I’ve almost got them figured out!
Good luck!
Gravity systems can be recognized by the much larger pipes.
They may have been updated with a new boiler and pumping system.
A barometric damper would be there if it is oil fired.
You may find them old gas burners to Micheal
Checking for seepage, drips and leaks (anywhere on the boiler or pipes, etc.) is advisable, too.
Type MG-1 Barometric Damper Control
Consumer Products
http://www.nationalcomfortinstitute.com/members/images/products/MG1B.jpg
Information: A double acting control for gas fired furnaces and boilers is widely used for conversion burner installations, gas draft-induced appliance operation with mechanical draft inducers or sidewall power vents. It is also recommended for use on gas atmospheric appliances where a draft hood can not be installed, and can improve combustion stability and draft on many gas atmospheric installations with venting problems. A double acting control for gas fired furnaces and boilers is widely used for conversion burner installations, gas draft-induced appliance operation with mechanical draft inducers or sidewall power vents.
It is also recommended for use on gas atmospheric appliances where a draft hood can not be installed, and can improve combustion stability and draft on many gas atmospheric installations with venting problems. The MG-1 provides precise, accurate control of drafts at levels higher than permitted by a standard draft diverter; a frequent requirement with gas. Because it is double-acting, it opens out to relieve positive vent system pressures as low as .001." Draft adjustments using weights are simple and accurate from .01" to .1."
• Solves many venting problems
• Works in a variety of situations including conversion burner installations or gas draft induced appliances
• Double action control
• Includes draft adjustment weights
• Available in 3 different sizes and special order sizes available to 32"
• Includes collar (available in sizes from 4" to 32")
There should also be:
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Pressure reducing valve on water supply pipe
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check or backflow valve on the water supply pipe
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Pressure relief valve and piping
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Expansion tank
If the unit has been upgraded or is a newer replaced unit, there may be:
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a domestic hot water immersion coil and hot water tempering valve
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zoning and zone valves