Two boilers control 17 zones plus indirect storage tank

itdpt

Problem is the two boilers are siamesed together and go on simultaneously making an incredibly annoying noise where the check valve is. I feel like they are fighting each other and were designed to go on one at a time not simultaneously for example if one boiler were to fail. But anyway here are pics. 

nicholas bonham-carter

What is controlling the system-thermostats, outdoor reset, or something else?—NBC

hot_rod

that piping at piping is referred to as bull heading, not a great way to combine boilers. A parallel boiler repipe and two boiler staging control would be a good upgrade. Spin the circ also, motor should be horizontal.

Zman

Each boiler should have it's own check valve. A spring check would be quieter. Normally the boilers would run independently. Both would come on only when needed.
Which tekmar controller is that? Is the big sensor strapped to the pipe an outdoor sensor painted black?

Dave T_2

I really like this piping and have used it many times. Boilers can be run independantly and staged easily.

hot_rod

one of the best ways to pipe multiple boilers is like this. The separator serves 4 functions, air, dirt, hydraulic and magnetic separation, no checks required either.

itdpt

The problem is they sometimes turn on at the same time and the check valve makes a terrible noise constantly as the pumps stay on. Is there a way to make them turn on only one at a time? 

Alan (California Radiant) Forbes

The best solution is to replace the check valve with one that doesn't make noise.

https://www.caleffi.com/usa/en-us/catalogue/serviceable-flow-check-valve-low-lead-na51200

Dave T_2

@Alan(CaliforniaRadiant)Forbes thats a nice looking flow check. Have you used it often and have an opinion about operation and the abilty to clean it?

Alan (California Radiant) Forbes

They came to my attention recently, promoted by a Caleffi rep. who frequents HeatingHelp. I had been looking for a spring check valve that wouldn't chatter and was easy to service. Check valves were a component that was troublesome; they would chatter, they would fail and they were difficult to service or replace. I'd never seen one that had unions and that was what won me over. So far, I'm very pleased.

They're not cheap, but definitely worth the price.

itdpt

itdpt

Thats the check valve right? When I took off the insulation it was directional having an arrow pointing towards the first primary boiler. Are they meant to fire at the same time? It seems to me when they are on at the same time the flow is creating turbulence in flap valve and it seems counter intuitive. What gives???

hot_rod

Classic example of why hydronics should not be bull headed, two flows pumping at each other on the run of the tees.

Then other issue, I suspect that is a swing check sized the same as the piping. If so it is oversized and the circulator is not able to push it all the way open, so the gate is swinging around. So with that piping I would run one at a time, valve off the one that is not running.
IF you need both to run at the same time, might want to repipe.
Piped parallel like this you would not need checks.

itdpt

How would I make it so that only one runs at a time. I believe the secondary is there just as a backup but I may be wrong.  initially thats how it was but then someone played with it and they run together making the constant flap noise.  

Alan (California Radiant) Forbes

You might already have something there to control the boilers. Can you give us the model number of the Tekmar control, the one in the blue box just above all the other controls?

hot_rod

itdpt said:

How would I make it so that only one runs at a time. I believe the secondary is there just as a backup but I may be wrong.  initially thats how it was but then someone played with it and they run together making the constant flap noise.  

A heat load calc would be a good way to know how much boiler you need. Hard to guess if both boilers need to run together. The piping is not ideal for both to run together

itdpt

Thanks for all the help guys. Here are 2 more pics of controller and actual boilers. I remember a time when only one boiler turned on and it was quiet check valve was not making noise. Now it seems both turn on with their corresponding circulator pumps. Also how do I lower the boiler temp to 180? Seems to go close to 200 at times. Another problem I have is DHW demand to indirect tank seems to never get satisfied with both circulators turning on eventually everything turns off but it takes hours and hours for the valve to finally close. TIA 

Alan (California Radiant) Forbes

There are a lot of issues with your system. Is there someone reliable that has been servicing and troubleshooting what you have there? If not, tell us what part of the country you're in. Maybe we have a qualified recommendation.

itdpt

I'm in staten island NY

itdpt

Alan what issues do you see?

Alan (California Radiant) Forbes

Check valve replacement and boiler control are your main issues. And I'm scratching my head to understand the piping logic, like why is there a check valve on only one boiler return? You also mentioned that it takes a long time to heat the DHW tank.

At the top of the page, there's a "Find A Contractor" link and I see that there are a few on Staten Island. Everyone's busy right now, so it may take awhile to get a visit.

hot_rod

A few other comments, the small circ should be rotated so the motor is not up.

Seems like a small expansion tank for two boilers and a lot of piping, how does the pressure look when it runs?

Also, that 4 way mix valve really needs an actuator to do a good job. On cast iron boilers that valve serves as both a mixing valve and the boiler return protection. It needs to be able to move on its own to serve the purpose.

If you can find a tekmar savvy contractor to troubleshoot and go over the settings. The tekmar rep on LI, Rathe and associates is excellent, maybe they can guide you to some tekmar gurus.

It could use some piping upgrades, not sure how deep you want to get into rebuilding it?