Second floor piping

kframe

Gravity system is easy to identify... No circulator pumps at the boiler.

The 2.5" pipe sounds like it could be either a gravity system or a forced circulation system.

Matt_7

Second floor piping

I am looking to install underfloor radiant heat in my first floor. I would then remove the existing cast iron radiators from that floor. The second floor has 5 rooms with a radiator in each room. Each radiator supply and return is piped to the basement (exposed through the first floor about 8" inches apart). My question is this - what is the best way to plumb the second floor radiators back together as a loop in the basement? I am looking to install a gas boiler and zone the second floor seperate from the first floor radiant heat.

Steamhead

Those exposed pipes

were actually a status symbol in the old days, Matt. It was one way to show you had the latest & greatest equipment.

You may have an old gravity system there. These systems did not originally use pumps- the water circulated by temperature difference. The pipes were big to keep resistance to a minimum.

I have a similar system and wouldn't trade it for anything. If yours is not heating well, you may have a problem with air accumulating in the radiators, or the circulator pump may be the wrong size (doesn't matter if it came with the boiler). Or a piping error may be starving some radiators of the heat they need. All these can be easily fixed by a knowledgeable Wethead.

You can also zone your existing system by using Thermostatic Radiator Valves. No repiping is needed with these units.

If you do undertake a major piping job, you should be able to supply any radiator up to 100 square feet with 1/2" pipe.

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Matt_7

I think it was a gravity system. It has (2) 2.5" pipes running around the basement with the existing radiators paralleled off of them. I'd like to remove all the big pipe and reconfigure. The pipes going up to the second floor are all 3/4".

Steamhead

It was gravity, all right

One thing to consider: with the right boiler, that system will work without electricity (think Enron). If you take out the large mains, it won't.

This may or may not be a consideration in our lifetime, but you never know..............

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Mike T., Swampeast MO

If you can at all tolerate the physical presence of the radiators I'd suggest keeping them. With thermostatic radiator valves (TRVs) and constant circulation their generous sizing will have comfort rivaling pure radiant heat with the ability to make quite rapid changes in room temp. Each and every room will become its own "zone" receiving just the amount of heat required to maintain the desired setting.

This is neither a particularly expensive nor difficult change to make as valve geometry is identical, it requires no wiring and only minor piping changes around the boiler. Installing radiant downstairs would likely be MUCH more expensive and you might still need radiators as older homes generally have more air infiltration and larger windows than newer homes--these often combine to make supplemental heat a requirement lest you overheat the floors.

Smallish radiant zones (think bath, laundry, etc.) can though be incorporated into the system rather easily and inexpensively.

Matt_7

Actually my main question was this: Since all my second floor radiators come down to the basement with 3/4 supply and returns would a one pipe system with monoflo T's be the best way to make the second floor into one zone? Or could I run 1/2" to them off of a supply-return manifold like the radiant systems use? (one circulator to supply the manifold) Which way is the best way? Thanks

Steamhead

Run them 2-pipe

not Monoflo. The end of a Monoflo loop gets cooler water than the beginning, and the radiators must be a bit bigger to compensate.

The manifold should work fine.

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