Red Valves on my hot water loop

JaymeHart

I have a single pipe steam system for most of my house, but a hot water loop for one radiator in the kitchen (added during a renovation). That radiator is upstairs, and had a blending valve contol to make sure it didnt feed overly hot water through the water loop causing flash steam when pushing the hot water upstairs.

I recently had the boiler replaced, and they eliminated the interconnection between the two pipes and blending valve. It is now just a straight supply and return, with 2 red flow control valves on each side of the hot water loop. I think they are Bell and Gossit Flow Control Valves. https://www.supplyhouse.com/Bell-Gossett-107019-1-1-4-Straight-Angle-Flow-Control

What do these flow control valves do? And are they an appropriate replacement for a mixer loop? Especially if the water is near 212F from the steam operation?

My plan is to re-wire the boiler with my Taco 503exp4 so that Steam is the Priority Zone, and the Hot Water Loop is then connected to a regular zone, but deprioritized during a Steam cycle. I hope this helps reduce any flash steam issues in the water loop.

But first, I need to understand what those red valves do.

109A_5

"My plan is to re-wire the boiler with my Taco 503exp4 so that Steam is the Priority Zone, and the Hot Water Loop is then connected to a regular zone, but deprioritized during a Steam cycle. I hope this helps reduce any flash steam issues in the water loop. "

This may cause other issues, like overheating the steam zone. Since the boiler is going to boil very quickly with only the load of one hot water radiator (priority or non-priority will still fire the boiler). You really need an aquastat to limit the boiler water temperature during a hot water call or put the blending valve back in if that worked well.

Those valves are like a specialized check valve.

mattmia2

you need to add the bypass

those are flow checks, they prevent gravity circulation. many wet rotor circulators have the option to put a flow check in the circulator body.

the function of the bypass is completely different. it mixes some of the return water with the boiling boiler water to keep it from flashing to steam with the pressure drop in the circulator.

if you wanted to do it with controls you'd have to have an aquastat in the boiler that turns off the hot water zone's circulator until the boiler temp drops below 190 or so. you can see that this isn't really a practical solution.

there should also be an aquastat that fires the boiler somewhere around 180 that is controlled by the hot water zone to heat the boiler for the hot water zone.

109A_5

Using the SR 503-EXP-4 with an added (high limit) aquastat. The aquastat limits the boiler's firing until the water temperature drops below the aquastat's set temperature. With only one radiator in the kitchen the boiler may not need to fire much to satisfy that zone, but if it needs to it can.

An aquastat example.

https://www.supplyhouse.com/Johnson-Controls-A19DAC-1C-Temperature-Control-100-240F

JaymeHart

thanks. they did add an aquastat to the hot water loop. a Presideo.

https://www.supplyhouse.com/Resideo-L4006A2007-High-or-Low-Limit-Aquastat-100-240-DegreeF-range-5-30-DegreeF-Adj-Differential-L4006A2007

I assume this aquastat was to fire the boiler if the water temp was below 150F ( which it is set at). It is wired inline to the water loop thermostat right now via an RA832A. I intend to replace that with the Taco wiring exactly as you describe 109A_5.

For the red flow checks, the prevent gravity circulation? Right now, the hot wster loop thermostst is off (I dont trust it yet). but the hot water radiator is warm. I was assuming that was gravity flow...

I really do Think I need that mixer valve added for safety.

109A_5

It seems like what is happening is what the valve is meant to prevent. I assume it is installed and set up correctly.

Using the SR 503-EXP-4 will alternate the boiler use for the two independent zones. Use of the mixer valve will help to prevent pump cavitation and flash steam issues if there is a kitchen call for heat when the steam priority ceases.

https://heatinghelp.com/systems-help-center/how-to-run-a-hot-water-zone-off-a-steam-boiler/

mattmia2

are the flo checks in the closed position?

mattmia2

you aren't going to control your way out of the hot water loop being mispiped unless you hold off operation of the circulator until the boiler cools enough to prevent cavitation.

why don't you make the installer fix the piping? the diagram of how it should be piped is on this site and probably in an issue of idronics and the boiler manufacturer's technical literature.

EBEBRATT-Ed

@JaymeHart as you have already figured out you need the bypass mixing loop for this to work. Any time you make steam the boiler water will be 212 degrees so it will flash.