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High-tech zoning for hot water radiators.

My 1910 home has some 15 hot water radiators on three floors with a single boiler in the basement and one thermostat centrally located on the first floor. The system is well maintained and air-bled before each heating season. On a really cold day here in Buffalo, NY, there can be more than 10 degrees difference in temperatures from room to room. I am sure this is a common problem many owners of older homes face. I would like to find a high-tech method to effectively zone each radiator’s area. Is there a way to add wall-mounted programmable thermostats near each radiator to send information to motorized radiator flow valves (does something like this even exist?) that would prevent the warmer rooms from overheating while giving the colder rooms a chance to reach a comfortable temperature? Even at a couple-hundred dollars a radiator, this would be far less expensive that replacing an entire heating system in a 5000 sq foot home.

Re: High-tech zoning for hot water radiators.


There's no need to replace the system.

It's most likely just out of adjustment; hot water systems need periodic adjustment.

Let's make some adjustments first.

The first thing you should do is to bleed air out of the rads, starting at the top floor.

Open the little bleed valve on each rad----if you get air, they probably all need bleeding---but you should ALSO GET WATER EVENTUALLY from each rad on the top floor----if you don't get any water from the rads on the top floor you don't have enough water pressure getting to the top floor (this can be easily adjusted).

Also make sure all the on/off valves on each rad are fully open.

Bleed the rest of the rads on the lower floors til water comes out.

From the description in your post it sounds like the rads are tied together in series, or, more likely, you have a main branch from the hot boiler supply to each floor, then direct connections to each rad on each floor, or diverter valves, then main branches back to the cold return on the boiler.
Are the supply pipes going up to the floors & the rads visible in the boiler room/cellar????

Can you see any balancing valves/ball valves for each of the floors to adjust the water temp to each floor???
Sometimes these are on the return piping before it goes back into the boiler.

Sometimes they have no handle on them, but only a screwdriver slot to make the adjustment.

(Note: the main hot water supply pipe comes OUT of the TOP of the boiler & pumps hot water TO the rads; the main RETURN pipe returns the cold and not so hot water FROM the rads & returns it to the bottom of the boiler so it can be heated up again).

If there are any of these balancing valves present, try adjusting them so you get equal heat on all 3 floors.

If you can equalize the heat on the FLOORS, make sure the control valves on each radiator (if they are present) are opened fully on the rads that are not producing enough heat.

See if there is any improvemnt after the valve adjustments.

There are thermostatic radiator valves that require no electricity (TRV's) that can be installed on certain radiators (if you have no control valves on the rads), but do your valve adjustments first to see if there is any improvement.

This sounds like a 200k btu/hr or better output boiler, is it listed on the boiler?

Is there a single circulator pump, or 3 pumps on the boiler???

The ideal fix is to have zone valves installed near the boiler for each of the 3 floors, with a t-stat for each floor----this saves a lot of fuel & affords good customer temp control of each of the floors, & is not that expensive to install.

Are you able to do any of this diy work yourself???

Please post back.

Re: High-tech zoning for hot water radiators.

I'd like to bring this subject up again as our situation is similar, though we only have 2 stories. As we are empty nesters 2 of our 3 2nd floor bedrooms are now multi-purpose so that day time usage is quite common particularly when the weather is cold/bad. Contractors that I've had come look at this either suggest re-piping in the basement to make an entire zone on each floor or use danforth type radiator valves. The problem with creating an entire floor zone is where to put the one thermostat as we have a fairly open stairway to a small hallway. The danforth type controls won't turn on the furnace when the room is cold.

I think Honeywell has controls that will do what I want but it seems that as a non-contractor I can't get real access to a sales outlet to verify that they are indeed available and what the pricing would be. I've even had two contractors listed on the honeywell site for my area come look at this project and they haven't really responded. Though I would think there would be a market for such controls in this day and age of high costs and still plenty of older homes around.


Re: High-tech zoning for hot water radiators.


In my opinion you would be better off with two separate zones with separate t-stats.

The t-stat can be placed anywhere, in or near one of the rooms and would give you the control of the heat in the upper and lower levels that you wouldn't get with Danfoss or Honeywell TRV's

All of this work (except for the t-stat) would be done in the boiler room--there are Taco zone valves or Taco circulators that are widely used for this application.

Patriot Supply has an online warehouse that sells these items.

There are numerous other plumbing supply houses on-line ---Google "plumbing supplies"; also Google "TRV" or "thermostatic radiator valve" for different mfgs & pricing for these valves.

The Honeywell TRV comes in two parts, an actuator, and the valve base for a total cost of ~$83.

Type in the following Honeywell numbers into their search box for pricing.

T104A1040, V110d1008


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