Thoughts?

Robert O'Brien

Haven't seen the job in person yet. Not a fan of the design.

Gordy

What's the radiant setup?

Bob Bona_4

That's some serious pumping going on. What is the logic behind that?

Dan Foley

Low loss header?

Robert O'Brien

Dan Foley said:

Low loss header?

I was thinking of a 4 way mixer?

Robert O'Brien

Bob Bona said:

That's some serious pumping going on. What is the logic behind that?

Not sure. Worked until a couple years ago and now high limit lockouts a few times a day. I'm assuming flow issues but it did work for years. One of the 15-58 may have taken a dump? I've never laid eyes on it

Robert O'Brien

Gordy said:

What's the radiant setup?

Haven't been there in person, entire house is radiant, all running the same temp, obviously!

Rich_49

Would love to see the source of that design . Wonder how much fluid that huge mixer will have to sift through to find the right temp ? Looks like fun Robert , will you be advising or installing as drawn ?

Any other documents ? Guess you'll be performing a heat loss calc for this one huh ?

Eastman

Is the system using ODR?

Harvey Ramer

I think it is a bad design. The differential bypass feeds right back to the inlet of the pumps. That could cause the water to get pretty hot in that loop when only a small zone is calling for heat. Premature pump failure.

Are the pumps staged?

4-way mixers are great when you need full flow from high temp to low temp. Since you are only dealing with low temp, I would consider injection mixing.

Harvey Ramer

Also, that check valve on the return is likely playing "hide and go seek" with the 3-way mixer.

Robert O'Brien

Rich said:

Would love to see the source of that design . Wonder how much fluid that huge mixer will have to sift through to find the right temp ? Looks like fun Robert , will you be advising or installing as drawn ?

Any other documents ? Guess you'll be performing a heat loss calc for this one huh ?

It's been in for 9 years, 60KW boiler. I don't need a heat loss to tell me it's way oversized.

Harvey Ramer said:

Also, that check valve on the return is likely playing "hide and go seek" with the 3-way mixer.

Spring checks all over the place. "Engineer" spec'd them

Harvey Ramer

You could always pull the internals out of the improperly placed checks and leave the housings inline, if that's what it takes...

Ironman

What induces flow through the boiler if the mixing valve closes off?
I can't see the logic for two 15-58's in parallel when one 26-99 would have worked. Redundancy in case one fails?

Gordy

Wondering if the original designers thought process with parallel 15-58's was some redundancy if a pump went down......obviously from the symptoms that was not thought out very well.

Eastman

The dual parallel pumps with bypass would produce a relatively flat pump curve. A flat pumping curve is/was the industry recommendation for zone valve systems.

The mixer must have been intended to be a high limit protection system only. Is the mixer set to a fixed temperature or does it use ODR?

I would guess somebody messed with the target temps causing either the mixer to throttle and/or additional zones to close, leading to a low flow condition in the boiler due to lack of hydraulic separation.

Paul Pollets

The system needs a low loss header and 1 pump, not 2. The flow rate is more than 6 gpm and while the 3 way mixing can be used, it's not necessary when only one temperature is required. The LLH with sensor will provide the correct setpoint temps without a mixing valve and motor. Primary/secondary piping is not used with Viessmann mod-cons.

Rich_49

But you will need a heat loss to know how to make it right Bob .

Robert O'Brien

Rich said:

But you will need a heat loss to know how to make it right Bob .

Sure, and when I tell him it's twice the size or more needed, he'll trash it and go for a new properly sized boiler!

Rich_49

And you'll still need a room by room . My point is that in any case a room by room is needed to do it right . You don't disagree do you ?

Robert O'Brien

Rich said:

And you'll still need a room by room . My point is that in any case a room by room is needed to do it right . You don't disagree do you ?

Rich has a penchant for sending nasty unsolicited messages. If you have something to share, just do so here. Since I will post them here anyway from now on, you may as well! Or you can just desist from sending me any messages at all, which would be my preference! You seem to be quite obsessed with what I do, where I couldn't care less about you!


Rich's message from today


"Figures ! By the way , I saw on another discussion where you eluded to performing 30- 40,000 boiler jobs . Did we add a few extra zeros in there or are you actually that good that you really do not need to perform heat losses like the rest of us ? Can I borrow your boiler elves ? "

Rich_49

Thank you Robert for posting that . I would have posted it publicly if not for Dan's requests last week to be more civil . Messages are not solicited per say , as opposed to sent from one to another .

Dan , please note that I did not display this publicly as per your request .

For the record Bob , I do not really have a problem with you as much as your penchant for stating that heat losses are not required in any circumstance it would seem . Although others may lack the Testi to state these facts I do not . We ask almost 100% of the posters if they have performed or had this performed yet you for some reason believe you do not require the same . My obsession is not so much with you personally , it is with you as much someone claiming to be a consummate professional that many listen to that does not perform the very first step required in performing a service properly .

Glad you posted my message so I could respond without fear of censure . I have much to say and contribute to anyone willing to listen and leave your antiquated ways in the past where they belong . There , you won't have to post this for me .

Robert O'Brien

You are anything but civil and your attitude obviates the value of anything you may have to say. Please leave me alone and I shall return the favor!

Eastman

So did the system get fixed? What's the plan?

Robert O'Brien

Still haven't been there. Will update

Charlie from wmass

pressure bypass is stuck open or set wrong?

Zman

I don't like the design either.
The dual circs make little sense.
The differential bipass in that location only flattens the effective curve of the circulators, it does nothing to maintain low through the boiler.
The 3 way mixing starves the boiler of flow when the valve modulates.
It looks like a wall hung mod/con. Why are they mixing to begin with.
Assuming it is a mod/con, I would think primary/secondary would work better than 4 way mixing due to the high head loss characteristics of the boiler.
If I was guessing as to "what changed", did the boiler scale up a bit so it now has very low flow and overshoots the high limit?
Was the drawing engineered or from a supply house designer?

Gordy

It's a wb2 15-60. So yeah why mix to begin with??