Heating Help

By less flexibility...

@ May 2, 2013 10:03 AM in Rumor has it

I mean that it's a fairly big box and you have to have room for the entire big box. In retrofit applications this may not always happen. In reality, it probably takes up less space than the equivalent system built out of parts. I hear you on people moving mechanicals out of the basement; hadn't thought of that since I'm far from any flood plane. I had actually looked at whether it would be possible to import a 333 some four years ago or so; at that point the 300 series were the only ones with lambda pro, they had better turn-down, the bus circulator, and were available with an actual indirect rather than flat plate + storage. That's how much I liked the concept - for myself. I decided that it was too scary to completely foresake any product support, even if it's something as solid as a Vitodens. ;-) So I'm not pooh-poohing the product.

Not so much a combi...

@ May 2, 2013 7:35 AM in Rumor has it

It has built-in storage (27 and 35 gal). It looks like it's meant to be a system-in-a-box. But it's a big hunk o' something! On the one hand, I can see the benefits of a well-integrated system... but, on the other hand, there are disadvantages, too. It is likely more expensive than something you'd build out of components, both up front and (especially) when something needs replacing. Also, you have less flexibility with tailoring the system to its various functions. And you have no flexibility with locating various bits to suit the space constraints. Let's face it, nobody in North America will put this thing in their kitchen or even bathroom, it will be in some corner of the basement where it has to fight for space with wiring, plumbing, and cat boxes.

I'm sure that specifics matter, but...

@ May 1, 2013 11:43 AM in Taking out a 3 yr old Navian..

What boilers have this wide a gap between return water temps and stack temps? I typically see a few degrees difference max on fire tube designs.

Fostapex, huh?

@ April 30, 2013 7:13 AM in I do not just work on steam boilers

And a manifold site-built from black iron pipe... must be an old timer. ;-)

How would you control the output?

@ April 27, 2013 9:10 AM in National Plumber Day!

I guess you could wire an outdoor reset control to some device that would make the steer stand up, as this would expose more surface area and produce greater heat output...

Maybe we could breed steer for increased surface area relative to volume. At the extreme end of that, you could imagine a living cowhide rug.

I don't know this boiler

@ April 27, 2013 7:29 AM in navien and odr?

But it seems that you can make this zone just fine even if it doesn't support both a heat demand input and the indoor feedback unit, just as long as you place the indoor feedback unit in your "most difficult" zone. This will then be the only thing that drives your system demand, and thermostats in other zones will only open zone valves for their zone without any feedback to the system. This is the same way TRVs are usually employed - since they don't have any end switches on them. :-)

I don't know, Paul

@ April 25, 2013 7:36 PM in Very Nice

You'd have to ask the people who wrote the manual. They contradict it in at least two different places.

If they could turn it down to 2', would you set it that way? That would be a good way to make sure that your higher head loss zones don't get the flow they need. Or you could balance your branches and have appropriate zone flow regardless of total system demand. Yes, I know, people don't balance their circuits, they don't do heat loss, they don't use outdoor reset or set it correctly, they don't calculate flow and head loss, they don't glue or prime their venting, they don't use oxygen diffusion barriers, they don't pump away... sheesh, scorched air is starting to sound pretty good! Luckily, now we have a product that will single-handedly right all these wrongs. But will it put down the toilet seat after someone leaves it up?

Of course it would work

@ April 25, 2013 1:31 PM in Very Nice

If it were set with H=5, then shut-off head is 4.5 and the pump would circulate roughly 1.5 gpm through that little zone. The zone would be overpumped by 50%, in other words. But that zone would be overpumped by as much even when all the zones are calling. And it would be overpumped by as much at near-design conditions no matter which circulator you use (yes, even the Bumble Bee) for one simple reason: flow has not been appropriately balanced.

Okay, then

@ April 25, 2013 10:17 AM in Very Nice

What happens to the Bumble Bee if you just put it in out of the box?

Or are you suggesting that figuring out where to place the two temperature sensors and how to plug them in is simpler than twiddling a dial? Yet, in the blog posts about dT, I don't see any analysis of what will happen if you just install this excellent product in an out-of-the box configuration - sensors detached - without bothering to read and understand the install instructions. Shouldn't he be more concerned with the proper installation of his own product than the competitor's? Why harp on this when a simple paragraph would do? Here's the suggested wording of that paragraph: "As with any control strategy, the benefits of pressure differential-based variable speed circulation will only be realized if the appropriate curve is selected. If set too high for the system, the variable speed circulator may constantly operate at full speed and overpumping may result, as illustrated in Figure X." A good location for this paragraph would be at the end of an article that honestly describes dP operation when parameters are correctly set.

We won't even mention the Alpha, a dP circulator that comes with the factory AutoAdapt mode selected.

It is the author's prerogative to write anything he likes any way he likes. All things considered, however, I find it impossible NOT to gain the impression that the way he chose to write this pooh-poohs a competing technology unfairly.

Not impressed...

@ April 25, 2013 7:58 AM in Very Nice

...with his choice to stick to his guns on analyzing what a misconfigured competitor's product does before he ever gets into what it will do if (presumably) correctly configured, and use the out-of-the-box clause as a cover.

Here's a realization: out-of-the-box, no circulator does anything useful except maybe act as a paper weight. You still have to, ahem, install it. Plugging it in is good, too. I'm surprised that this series of articles takes such a critical thing for granted...

Nobody is bashing the man, Steve

@ April 25, 2013 6:48 AM in Very Nice

I'm bashing the article. I see no evidence on this thread of bashing dT or setpoint circulator control, Taco, or its products. Seems to me like we all agree that there's an application for dT. (As an aside, as far as the setpoint mode is concerned, you could make it far more useful by using the other sensor as an outdoor sensor and providing a way to set a reset curve, which seems like it would be a software-only upgrade. But that's just my opinion.) But the article would certainly appear to bash dP circulator control, and do it in a fairly unfair manner. Anyone with a concern for the health of the industry and the passion for technology that John has surely aspires to a higher standard of fairness and accuracy.

There's a difference between stating that there's a target delta T for design conditions that's a good compromise between cost, energy efficiency, and performance, and that there shall be a fixed delta T for all conditions. I, for one, would like to see him discuss more broadly the implications of a fixed delta T operation compared to floating. He hinted at it in this article (suggesting that a dP circulator would run at the same speeds during shoulder seasons as it would during peak season) but a balanced and in-depth analysis of the two approaches (maintain flow but reduce supply temp further [floating dT] vs. reduce flow but reduce supply temp less [fixed dT]), both ways to attain the same AWT and therefore the same heat output, is what it's really called for and what has driven a lot of the discussions here. He may find it necessary to tweak his format a bit.

I'm not inclined to cut slack

@ April 24, 2013 4:07 PM in Very Nice

There are other products with clearer manuals out there. Also, as an expert, or at least a person with considerable expertise available to him at will, he should be far less dependent upon these manuals to figure out how these devices should be set. As a person of authority in this space he has a responsibility to the industry to present accurate information. I'd be far more inclined to cut slack if the tone of his article did not strike me as pretty condescending to the unwashed masses who are honestly trying to make sense of this technology (and apparently having more success than he, the expert.)

You're right

@ April 24, 2013 3:47 PM in Very Nice

Looks like shutoff head is not really H/2 but more like (H + Hmin)/2. So, rather than split the difference between H and 0, split the difference between H and Hmin. What this would mean is that at H=5 (which would be a good setting for this system) you'd basically have a near constant dP curve.

4' min is for H

@ April 24, 2013 2:58 PM in Very Nice

1/2 H is then 2' head. That's the shut-off head. For the circ to operate the way you describe it would have to be set for 8'. By default, it is set to 10'.

Chris

@ April 24, 2013 2:28 PM in Very Nice

My point is contained in the last sentence. Why would you intentionally misconfigure a product just so you can state that it doesn't perform?

Yet that, in my view, is what the blog's author did.

Apparently...

@ April 24, 2013 2:26 PM in Very Nice

...that dial is there so you can turn it up too high and then complain that the circ is operating at full speed and you're overpumping your system. :-)
Chris, I updated my original response to this thread with what would happen to the circulator's duty point if it had been properly set up for this system. I hope that answers it.

The Eco is only dP-v

@ April 24, 2013 1:27 PM in Very Nice

The Alpha is only dP-constant. Larger Stratos circs (among others) support both. The blog author was using the Eco in the context of dP circs in general.

I'm using it as I wish

@ April 24, 2013 11:06 AM in Very Nice

I am pointing out the limitations of his discussion and the misinformation in the information he's providing. I definitely do not wish to accept it uncritically. I'll leave that to others.

He is NOT merely providing information. It is quite clear that he has an agenda. What he is doing is analogous to someone intentionally oversizing a mod con so that minimum modulation is greater than the design heat load, and then saying "well, look, wouldn't you expect a modulating boiler to, you know, modulate?" Only it's even worse, because there's no red dial to turn down the min output on a mod con, and there IS one on the circulator that he's providing "information" on.

EDIT: Here, let me provide a more to-the-point analogy. Let's say that I use a Bumble Bee as my system circulator, set it to 5 F delta T, and put it in a fixed temperature, part-time circulation system designed around a 20 F delta T at 10 gpm and 7' of head. Not an unusual system. The Bumble Bee will never be able to reach that 5 F delta T so it will always operate at full speed until the call for heat is satisfied. Geez, wouldn't I expect my variable speed pump to, you know, vary its speed?

But why would I intentionally misconfigure the Bumble Bee? Yeah, my point exactly. 

Seems like he is laboring under some severe misapprehensions

@ April 24, 2013 9:42 AM in Very Nice

The pump is not varying its speed? How does he think that that important diagonal line that starts at 5 ft hd and goes over to 10 ft hd @ 9 gpm actually happens? Now, he chose examples that illustrate his point but these examples only make sense if we could not adjust the dP-V curve to suit the system. Which we can. His apparent inability to utilize the available control features to properly configure the circ for his system are not the circulator's fault.

Secondly, dP-V is not by far the only control algorithm possible; more common is the dP-fixed. Let's say that he set the dial to 5 ft hd. What happens now? Or, for that matter, even with a dP-V curve, if he set it so that it intersects the system curve at 5' head and 10 gpm. In the case of fixed dP (5') the circulator will now push 10 gpm when all zones are open (curve A) and about 6.25 gpm when the largest zone closes (curve B). In the case of dP-V adjusted to the system (which will vary head between roughly 5.5' @ 12.5 gpm and 2.75' @ 0 gpm) the circulator will push 10 gpm when all zones are open (curve A) and about 5.5 gpm when the largest zone closes (curve B). Meanwhile, a fixed speed circulator with the same hydraulic performance would, as he says, be pushing 11.5 gpm (A) and 9 gpm (B). There's a world of difference between the performance of a properly configured product and one configured for the purposes of a punchline.

All this would be fine if the guy were actually asking a question, but it seems like he's pointing a finger. When pointing that finger, it's important to have one's ducks in a row. He doesn't.

Large thermal mass

@ April 24, 2013 9:09 AM in Outdoor reset

This has been seen by some who have put bang-bang boilers with just an aquastat as a control on old gravity systems or other large thermal mass emitters. The water temp never gets a chance to climb to the setpoint before the thermostat cuts out the call for heat. It does seem like a thermostatic boiler bypass would be a good thing under those circumstances.

That's actually a very interesting idea!

@ April 22, 2013 8:13 AM in Direct Pump TT Solo 110 with 3 zones

It had me thinking for a while - I don't think I've heard anyone mention running the sensors for the delta on boiler and system loops, and it's certainly not in their installation manual as an application. There are a couple of issues with it, though - firstly, if you really want balanced flow, the best way to get there is to get rid of hydraulic separation. Even for imbalanced flow with a fixed degree of imbalance, a fixed bypass with a balancing valve would be the way. It seems like you're trying to use complicated controls to do something very simple. The whole point of hydraulic separation is to NOT couple boiler flow to system flow.
Secondly, there's an issue with system feedback. You want the circ to respond to greater system demand by increasing the flow. What will actually happen is that, as zones open, you will get cooler return and more flow in the system loop at the same circulator duty point. Assuming that the boiler is good at maintaining its supply setpoint, this will now result in the boiler supply being mixed down some with system return, which your control algorithm would interpret as excess system flow and turn down its duty point until system supply is once again equal to boiler supply - but now at a lower flow. So the response would seem to be the opposite of what's required.

I'm using it with a reverse indirect

@ April 16, 2013 2:18 PM in Let's Try Again-TT Mini Smart

Turbomax 23 (and PS60), to be exact. This is with the MCBA, for what it's worth. It works pretty much as expected, but toward the end of the cycle it will REALLY turn itself down and v-e-r-y slowly finish "topping off" the tank. I have the "setpoint over water temperature" parameter set to something low, I'll experiment with bumping it up a bit. I think, but I'm not sure, that the DHW program has a built in boost function, based upon observing it exceed the prescribed supply temperature.