Uncontrolled heat in condo

ziggy12

Uncontrolled heat in Condo . Thermostat set to 72, room 76. New Honeywell RTH 7500. New Taco 572 on return line. Disconnected thermostat, room temp. stays the same. 4 story Condo building on 4th floor. Is it passible that Circulator head pressure ( unknown) is overcoming the Taco return spring force and keeping it partly open?

hot_rod

Depends on which model you have, here is the range.

feet of head ÷ by 2.31. 150 head ÷ 2.31 = 65 psi shut off.

That is ∆P not fill pressure. What is the system pump?

ziggy12

Thanks for the response, Not sure, the condo is 380 miles away. The Taco has only two wires connected. 1 and 2 terminal. I suppose it has a central circulator, not controlled by my zone valve. Old building. Bought the condo a year ago, had uncontrolled heat last winter also. At what head pressure is the valve forced open without the thermostat calling for heat? Are different strengths closing springs available for the Taco? 76 deg is the temp with the Thermostat disconnected ( wires free) If I reconnect the Thermostat and set it to 80 deg the heat will increase and stabilize there, indicating to me that the zone valve is working as it should but is being forced open by circulator head pressure.
Am I wrong?

hot_rod

flow up the return side is also a possibility, sometimes a check is needed on the return.

Large projects like that really benefit from delta P type circulators which adjust output as various zones open and close.

Or a pressure bypass can be added at the boiler piping, and the correct circulator size is confirmed..

ziggy12

I took the old Taco 572 valve apart. The closing part is a round disc at the end of a piston held against the seat by a spring, being positioned in the return line it acts as a one way check valve, thus backflow is not possible. I did not find anything wrong with it.

hot_rod

If you put your hand on the pipe or get a thermometer to strap on or infrared temperature gun, you should be able to determine if it is bleeding thru or getting reverse ghost flow.

Properly operating zone valves are 100% shutoff, within their design criteria.

ziggy12

Design criteria are the key words. Thus at what "head" pressure is it designed to open, without the Power head being energized, I don't know. Work on the installation was done by a plumber, hired by the condo association (52 units in Chicago)

hot_rod

At Caleffi we offer a range of zone valves based on the shutoff pressure the application requires.

Typically multi unit buildings with a single circulator have a higher shutoff valve installed. Our 1 Cv Z one valves have a 75 psi shutoff.

Low Cv, high shutoff valves are often found on air handlers, fan coils etc from the factory as they want the highest possible shutoff as they are not always advised to the type of circulator they are working against.

If the pipe downstream is getting hot with the valve powered down, either something is stuck, even teflon tape shards will cause enough leakage. Or the valve is incapable of shutting off against the system ∆P.

Temperature, and or pressure gauges at the valve would confirm this.

ziggy12

In Condo living Heating is considered "Common Element" and my monthly assessment fee pays for it. Although I own the unit I may not do any modifications except for the thermostat, that is my responsibility. It is new.
When I complain about the heat to management, I get smartass advice. "Open the Window". I don't intend to do any work on the system, just want to be informed when I talk to the plumbers, even they don't seem to know where is the problem that is causing the uncontrolled heat, they changed my zone valve but it made no difference. All zone valves are in the first floor passage ceiling, my unit is on the fourth. Boilers in the basement were upgraded 3 years ago.

ziggy12

Thank you hot rod 7, for pointing me in the right direction. I will not be able to investigate the heat again until shortly before Christmas, when I will be at the Condo again. I propose to do some experimentation then by disconnecting the thermostat and observing at what temperature the heat will settle with the new Taco 572 after an hour or so. If it is at 76 as before, I will reconnect the thermostat, crank it up to 80 and see what happens, if there is any debris on the seat, it should be blown out with the zone valve wide open. I resent being told by the Board to open a window.

question

The unit is above another and heat does rise. The heat is not uncontrolled. It's only a 4 degree difference. I live in NYC. The buildings are overheated to 80 plus degrees. Don't sweat the small things .

ziggy12

I beg to differ with your statement that the heat is not uncontrolled. I use a Honeywell programmable thermostat RTH7500D, it is set to reduce the heat to 70 deg for sleeping at night and yet it stays at 76 deg, even with the thermostat removed. Thus indicating that hot water is circulating in the baseboard pipes, they are warm to touch. There is a manual shutoff valve at the entrance to the baseboards, when I close it, everything cools off.

hot_rod

This is not an uncommon situation in condo projects with single pump and multiple zone valved units. Sometimes poor design, sometimes mis-applied components, and sometimes caused by changes made over time, wrong pumps substituted for example.

My son lived in a condo in Colorado with the same issue, and as a rep he saw it over and over.

It took some convincing to make the HO board believe that a huge gas bill reduction would payback by upgrading and fixing years worth of bad repairs.

Gas and wood fireplaces throw a wrench in the works in rental condos also. Start a fire when the room is at 70F and windows are open, fireplace and heat running all at the same time:)

ziggy12

I am one of those people who expect equipment to operate as designed and my moto is "any job, big or small, do it right or not at all" .