Hot water radiant heat ?????

I have an inspection in the next few days for a realtor who is buying the house. Just met her last week.:cool:

She tells me it has hot water radiant heat. I don’t run into these systems very often and I THINK I forget what to look for, aside from leaks.

Any suggestions?

If this is central heating, which we have in the UK and is far better than the blowing air solutions you use in the US, piping hot water on a closed system to white radiators from a gas-fuelled boiler then you could consider the following:

Check each radiator can be turned on and off. They may need bleeding.

Check the thermostat works (sometimes these are attached to each radiator)

Drain a pint of water from the system as a sample and check the colour.

  • A dirty grey colour is normal.
  • A dirty black colour indicates some sludge.
  • A rusty colour indicates some corrosion.
    If there is any indication of sludge or corrosion, a corrosion inhibitor needs adding.

Lime scale builds up on the inside of the boiler’s heat exchanger which reduces the boilers efficiency and can cause the boiler to make a banging noise.

Check the pressure in the system. Should be about 0.7 - 1.5 bar. Too much pressure can put a strain on the pump. Too little, I am not sure what happens but most systems close down and it could be evidence of a leak.

Actually, just looked it up and it might be underfloor heating you want. So please disregard. Sorry. I guess radiators are a bit too advanced for the US (as is putting power cables under the ground to greatly reduce the incidence of weather-related outages)!

Underfloor heating. Ouch, that’s gonna be expensive.

Thanks for your thoughts Ian.

She says it is an older home so I think it may be radiators like you have in the UK, not the newer underfloor systems like in America.

BTW Whitby Ontario is in Canada:mrgreen: , we have buried electrical cables too!:stuck_out_tongue:


Off to the pub I go!:wink:

I’m going North for the winter! (I live in Washington D.C. now). :smiley: And I love this country except for the power lines, and air blown heating. Oh, and 110 volts sucks (it was fine until I tried to buy a dryer and was introduced to the concept of a gas model for those without 220 supplies). Gas dryer? Crazy. Sump pumps? Build up, not down.

And life would be so much easier if wires were joined with these

rather than these

I’ll stop now.

Armored cable IS a good idea. It’s seen as too expensive in most countries.

Am I off-topic?

I would also look for any signs of moisture damage under the shut off valves which often leak.

Thanks Erol

I was more interested in things at the boiler. pressure guage? check valve?
that kind of thing, signs of impending doom/failure? etc.:shock: :shock:


Doug; There is an old saying ( even a Blind hog can find a acorn occasionally) Water leaks are obvious. If I was inspecting I would be looking at the safety’s Is the pilot light a fail safe. What kind of gas valve is in use as the controller. Does the make up water have a control device is there a sight glass in use does it leak. Are there any relief valves in use are they corroded up when was the last time the relief valve was changed out. The list goes on and on

A water leak visible at the time of inspection is an obvious no-brainer. The damage to a floor from previous leaks over a long period of time may not be. Some of those old wood floors are as soft as a sponge under the valve. I never said not to inspect the mechanicals.

Thanks for the help guys, as I said in the first post , I don’t see these systems very much. I was looking for a refresher
Thanks again


I’ve had underground service for 30 years here in the good old U.S.A. and we have sunshine too. :cool:

Here’s my inspection protocol for the boiler portion of the inspection of hot-water systems, put together from various sources.

I welcome any comments, corrections or suggestions:

Check for Sight glass and/or low water cutoff: If so steam, conversion, or hybrid system.

**Describe as Open or Closed System: **Closed (forced) system will have circulation pump.

Observe piping: Closed system with over-sized pipes pitched toward boiler usually means a conversion from older open system, may be missing safety devices.

Observe Expansion tank:** If open system: **3" above highest point of system and vented
**Observe Pressure Relief Valve:**30 psi , piped to w/I 6" of floor
Watch for plugged valve
Must be on boiler side of devices such as pressure reducing valves.
**Observe High Temp Switch:**Hi Limit: Typically 210F. If higher, suggest service. Above 250F is likely safety hazard.
Lo Limit: Typically 110-130F
**Observe Backflow Preventor:**Observe location: Should be on cold water supply upstream of pressure regulator.
Observe Directional Marking: Should point toward boiler
Observe If Pressure Reducing Valve Installed: PRV (AKA auto make up valve or feed water pressure regulator) is not required, it is a convenience.

**If Closed System:**Observe Circulation pumps(s):
Direction plumed
Past or present leaks
Oil level
**Observe drain valve: **Missing or closed is defect – often modification of older open system

**Observe Evidence of past/recent repairs. **Service tags?

Observe Draft Diverter/Hood: Check inside for corrosion, scorching, and back-drafting

Observe Piping Material.

Observe Piping Type:- Two Pipe (AKA Loop): circa per 1950 large diameter pipes, two runs each with capped end.
- One Pipe Monoflow: circa 1950+, 1-1/4" iron or copper pipe,

  • Mainless loop systems: circa 1960+ , baseboard, zoned groups in series. (ex: loop, monoflow, mainless)
    Observe Piping Insulation: Possible asbestos?

Observe Boiler: cast or welded (cast iron will not have welds at pipe connections).

**Observe at least one cycle:**Record: thermostat settings

Observe and Record Temp/ Pressure: At start and after running 15 min:[INDENT]Start ___ / ___
Run ___ / ___
Off ___ / ___

Normally 12 psi cold, 16-22 psi hot, and 160-200F
18psi+ and/or 200F+ requires HVAC inspect.
More than 5 psi rise may mean waterlogged expansion tank
Observe Relief Valve, **do not operate: **Check for leaks

**Observe Drain valve, do not operate: **Check for leaks

Observe Circulation pump: Check for operation / leaks

**If copper tube boiler:****Observe operation of pump: **pushing water through tubes when burner is on.
Observe Burner pattern

Observe Operating Sound - Any unusual noises during operation?

**After burner shutdown:**Observe any dripping water: from heat exchanger (indicates leak)
Observe any steam: (indicates leak)
**Listen for hiss: of evaporating water from leaks (indicates leak)
** Restore thermostat settings

Mike good post

Thanks Mike::cool:

Just what I was looking for.

I did forget a few things;) But oh well, I am a senior citizen.


Very nice Mike, thanks for sharing that