Can't get the 4th zone to heat. What System is this?

Joseph_4

Can someone, please tell me what to do. Went to customer today. boiler with 4 zones, zoned with pumps. drained system to change ruptured expansion tank. filles system bled zones from boiler room. has hose-bib and ball valve for each zone. go around to bleed radiators and  THERE ARE NONE. customer tells me they used to have, but now  they switched it to  a hot air system with ducts. she brings me to a closet across the room and there is an hvac unit. the copper pipes  or at least some go from the boiler to the hvac unit. I have no idea how this system works. The 4th floor (its its own zone) wont get hot. the other 3  are getting hot. Can someone please explain this system, and tell me what to do for the 4th zone?

Timco

hydro air

What you have is hydro air. The coil in the fan unit will have a bleeder, or you can ramp up the pressure and purge through that hose bib after closing the valve downstream of it.



Tim

Joseph_4

... felt pipe near hvac unit and its hot

The 3/4 copper pipe in closet by fan unit was hot. and why are the first 3 floors getting hot? Is there a seperate coil for each zone? 

JStar

A couple things.

What pressure is your boiler running at? It should be at least 24 psi to get water up to the fourth floor.



How are the zones piped to the boiler? Are all of the pumps in the boiler room? Can you find a Delta-P (foot of head) and GPM rating for the hot water coil?



I'm thinking that the fourth zone pump is trying to overcome too much resistance in the coil and four stories worth of piping. If you find the numbers for the head on the coil, and the equivalent length of pipe, compare that to the pump curve for whatever pump you have. You may need to create a secondary loop with a separate pump just for the fourth zone. That would mean, disconnecting the coil, have the existing pump just take care of the vertical piping, and tee a loop near the air handler with a separate (smaller) pump just for the resistance in the coil.

helpingothershelpthemselves_2

Hydro air / hydro coil ZONE

Yossie,

Check your email .

Ken Resnick

heatboy

As stated, static pressure......

will need to be raised substantially to get the water that high.  Is it really 4 floors?   24 PSIG of boiler pressure and I'm sure it only has a 30 lbs. relief valve.  Is/could the boiler be rated for 50 PSIG?  At 24 PSIG, you will need to use a larger compression tank because you have reduced the amount of expansion room in that #30 since the tank will have to pumped up that high, also.

helpingothershelpthemselves_2

Air Handler Zone

Or we can keep it simple .........

Considering the poster ONLY REPLACED a compression type expansion tank.......Then "seemed" to have this issue .......

Was the affected zone working properly prior to you replacing the defective expansion tank ?

What is your system operating pressure ?

Is the air handler (blower) coming on when the thermostat for that zone calls for heat ?

What size was the "defective' expansion tank . (i.e. #15 , #30 )

What size expansion tank did you replace it with ?

Joseph_4

it was a t60 expansion tank

size of tank was a t60. The safety relief valve is a 30

JStar

Did you...

...size the tank to the system? What is the boiler btuh output? And what make/model boiler?

Coany

manually turn the blower on at the thermostat.

did it come on? is it blowing warm air?



take the cover off the blower and look for a coin vent on the hot water coil itself.



you've got to check line for line voltage at the air handler.



It could be the fan switch,

 Thats what your checking by turning the fan to the "on" position at the thermostat.