Mixing Valves and Zone Balancing Issues

AKDISTILLER

I have two side-by-side buildings that used to be individually heated with steam boilers in one and a water boiler in the other. I’ve attempted to simplify my life by instead heating the two buildings from one water boiler in my smaller building, connecting both buildings w/ 1 ¼” Rehau INSULPEX. I’m having issues with this recently tweaked system: it is not performing correctly. Can you guys help me figure out what I need to tweak?

I used to run the large building off two steam boilers and the small building was a simple pump and manifold. They were operating fine separately. We still have the steam boiler system, but now it is only used for running Stills for distilling. So the systems were already in place and installed. The changes we made were connecting the two buildings, adding a base board heater in the office, and re-doing the near boiler plumbing.

Being the larger building (3300 sq. ft. radiant) was designed w/ 4 zone valves and one circulator to run off a steam heat exchanger, all I did there was tee into the supply and returns and valve off the heat exchanger.
The small building, which houses the new water boiler, is 1400 sq. ft. radiant and one 10’ base board emitter in a little office.

When the office baseboard zone is on (which is a very short run above the boiler room) only one or the other radiant floor or other building zones gets hot supply. It’s like the pump’s too large (TACO 007e) or I need balancing valves. The other issue is with the TACO 3-way mixing valves as they just constantly chase their target temp and don’t come close (80-140 degree swings). I’ve disabled them and now control the supply temp with the primary circulator set to a target temp of 110 deg. on secondary side, which seems to average an actual average supply of 115-120 deg. What am I missing to make these 3-way valves work and not have the office take the supply to one of the other zones when its running?

The system is set up with primary/secondary piping split through a heat exchanger. The secondary is glycol w/ the boiler primary side being water. The goal was to run the secondary at 130 deg. and mix it down w/ iSeries TACO 3-way mixing valves. The office base board is over sized for 130 deg. supply and doesn’t need mixing. All circulators are Taco 00e except office baseboard 007E. A couple red flags for me are

1. The two circ. pumps for large building (one installed just after mix valves and the other 100’ + away in the other boiler room) ran in series (first pump set at 30 deg. Delta T and second pump set at constant speed mode 2.
2. Two pressure tanks, one in each building.

I’m in a remote Alaskan village and have had to work with a supplier 700 miles away, a local plumber not too keen on the supplier’s design, and an install in the middle of extreme winter weather. I’m able to heat the buildings now, but the system does not perform correctly. I am a builder and now maintenance man/distiller/business owner with limited professional support, so I’ve become an amateur boiler/hydronic enthusiast and maintain and tweak this system myself. I’m hoping you guys could take a look at my design and help me figure out what needs tweaking.

GroundUp

Of course you need balancing, and unless the iSeries mixer is tied to ODR I'd throw it away and switch to a standard 3 way thermostatic mixing valve so it's set and forget.

AKDISTILLER

The ODR on both iSeries valves is wired. Between the benefits the ODR adds and the $700 investment in the valves I'd like to figure out how to get them to work rather than "throw them away".

hot_rod

I'd move that supply sensor down away from the mixed port as far as the leads allow, also insulate around it. You need a couple feet of piping for the fluid to mix well and get an accurate reading. Motorized valves will always be hunting to some degree. It is important to size them properly so they are "ranging" in the middle of their stroke. When oversized they are forced to run with the ball in a near closed position, inaccurate and you may see excessive wear on the edges of the ball.

Ideally you would know what gpm is required on each and every circuit and have a means to adjust and balance. With multi speed circulators you can do some coarse balance.

Not sure how a delta T circ and motorized mix valve behave together, especially if that circuit is zoned also? The circ is trying to maintain a temperature range by changing flow, gpm. The valve is trying to mix with a stable flow on H & C. Seems like they may be at odds with one another. Try the circ in a fixed speed mode, maybe.