Variable speed ECM boiler pumps

Paul48

Digital controls make adding D to PI trivial, but that D coefficient is very sensitive. You can really muck things up with it.

"PICCVs are wonderful things -- particularly for solving issues with existing, poorly designed (or modified) systems. My experience tells me that when we pipe using reverse return, install properly sized CCV's for each zone (even on single rads) and ΔP pump the emitter circuit(s), everything works -- like magic. There's literally no balancing required.

We spend about $10 more on a small CCV with 2-10V proportional actuator than we would for a conventional bang/bang zone valve.

We drive each valve using a PID loop with the associated room temp as its input. The boiler or mixing valve(s) run on one or more ODR curves. When all (or nearly all, in some cases) of the zone valves are less than 20% open, we shift the reset curve down a few degrees. When some number (usually one or two) remain 100% open for more than five minutes, we shift the reset curve up a few degrees".



I'm sure the junior tech "on call" Christmas Eve, appreciates the simplicity. Honestly....when you start engineering from "A" to "B", by way of "Z", you're asking for trouble. I've seen it time and again, on custom machines. Unbolting a $50000 sub-assembly from a machine and replacing it with a $200 piece. Technology is wonderful, but the best design is always the simplest.

Gordy

The idea is really not complicated as far as components.

Gordy

It's just a valve with some lines of code telling it what to do in certain parameters.

Paul48

True.....It's not complicated until the coil on one of those actuators partially shorts out, and throws your calibration out the window. Or add a bunch of them to an already over- complicated system and they are from a bad batch. I know --it happens, but why ask for it.

SWEI

I'm not quite clear what risk you're expressing concern for above, but the direct-drive actuators have far fewer moving parts than most zone valves. I've yet to see a problem. but we do keep spares on the shelf.

Paul48

I'm sorry SWEI..........It was not intended as a shot at your application, specifically. It was more a commentary of design, in general. I am always the most impressed by simplest of designs. When you look at the work of the Dead Men, and can be amazed that they made things work perfectly without a wire. When you take a tiny assembly apart, and say....wow.....that's beautifully simple.

SWEI

Of course. The Einstein quote frequently comes to mind here.

I'm also hugely fascinated by the Dead Men and their work. I often wonder what they would have to say about some of the newer technology we have available to us, and what they would do with it.

Gordy

Well where is the line in the sand? Different line for different situations.

On the residential side it's as efficient, simple, and self sustaining as possible with lowest possible upfront costs to the homeowner. That should be the goal in all realms.

Like I said a while ago there are the select few geeks with deep pockets that don't mind a complex system with all kinds of rags giving them a sense (sometimes false sense) that they have the most advanced comfort system money can buy.

Average joe homeowner sees that same system as a complex headache of ownership, and could care less.

So HTPs UFT is taking some of the complexity away from the package, and putting it back in the hands of the designer...smart. Let the designer choose his own method, and not be strapped to an on board device. Keep the on board logic to communicate with a third party source, and controlling the output.

But let's keep to the fore front the spark that started the fire, and that's HE equipment married to high temp emitters, and trying to get that toted advertised efficiency. To do that has to bring some complexity of a small amount.......at least to be done in an hands off controlled manner.

In some scenarios a delta t circ may be all that's needed, in others maybe delta p controlled by a synchronized valve to give an exceptable flow rate to a boiler through out its range of modulation. The situations that will need P/S seems to be a bit of a disconnect from the discussions.

Gordy

SWEI said:

Of course. The Einstein quite frequently comes to mind here.

I'm also hugely fascinated by the Dead Men and their work. I often wonder what they would have to say about some of the newer technology we have available to us, and what they would do with it.

Can't get much more dependable than a heating system that only required fuel to operate, and not electricity.

Of course innovation is inspired by necessity. That's where the circulator came in. It decreased pipe size, and expanded the length of horizontal runs. When fuel costs sky rocketed then came efficiencies.

SWEI

njtommy said:

Honeywell t7350 I think is the numbers. It can modulate a heating valve.

The T7350M1008 will, but the cost on a single piece roughly matches that for a small networkable DDC controller plus two "stats" (sensor/display terminals) to go with.

The TB6980/7980 have modulating outputs and are priced right, but the PID coefficients are pre-set for an air handler coil and can not be tuned.

Paul48

The system should stand the test of time. If, for instance you are no longer in the business in 20 years, you don't want people that follow you to say...Oh My God.....That's one of so-and-so's systems, and tear it all out because they don't understand it. If it is so complex, you couldn't begin to explain its operation to a homeowner in an hour, it's too complex to be in a home. If it's in a commercial environment, a sequence of operation should be left with the system. Believe me, the maintenance staff would appreciate it. And, no, it would not cost you work. Exactly the opposite. No one stays at one job for life anymore, and the people that have come to see your systems, are moving all the time.

SWEI

We do think about that, and it's one of the reasons we base our systems on a well-supported BACnet compliant building automation platform instead of using a generic PLC. It costs more, but it can be networked with any BACnet-compliant device or controller -- and reconfigured or adjusted using multiple vendors' software toolkits.

SWEI

Gordy said:

On the residential side it's as efficient, simple, and self sustaining as possible with lowest possible upfront costs to the homeowner. That should be the goal in all realms.

Properly configured onboard controls in a modern boiler can almost do this. Where they fall down is the lack of proper indoor feedback (Viessmann excepted at this point.) Look at the level of sophistication offered by modern inverter mini-split controls and weep. Boiler manufacturers are you listening? We need to compete, and offering a proprietary "stat" that truly communicates with the onboard boiler controls will significantly increase both your bottom line and your customer retention.

there are the select few geeks with deep pockets that don't mind a complex system with all kinds of rags giving them a sense (sometimes false sense) that they have the most advanced comfort system money can buy.

I used to build stuff like that.

hot_rod

Paul48 said:

The system should stand the test of time. If, for instance you are no longer in the business in 20 years, you don't want people that follow you to say...Oh My God.....That's one of so-and-so's systems, and tear it all out because they don't understand it. If it is so complex, you couldn't begin to explain its operation to a homeowner in an hour, it's too complex to be in a home. If it's in a commercial environment, a sequence of operation should be left with the system. Believe me, the maintenance staff would appreciate it. And, no, it would not cost you work. Exactly the opposite. No one stays at one job for life anymore, and the people that have come to see your systems, are moving all the time.

What is the reasonable life expectancy of a boiler, pump, control package, etc on a hydronic system? 20 years? Better yet a troubler 20 years!

How often do homeowners expect to replace cars, computers and other common appliances?

I have HTP munchkins coming up on 20 years in the field, not a bad ROI.

If we want super simple maybe we look at gravity powered systems again. With the PP tube like Aquatherm, labor savings would be huge.

I agree with system documentation, that should be a code requirement and something inspectors look for on every job.

Dan Foley and many other top contractors include a nice doc package, load calc, piping layout and essay of operation. Digital pics of tube install, and everything in a drop box would be a nice touch.

Here is an idea from a Wisconsin installer, Northern Groundsource. Sure wish septic installers would latch on to this drone idea.

Eastman

We need to compete, and offering a proprietary "stat" that truly communicates with the onboard boiler controls will significantly increase both your bottom line and your customer retention.

I think proprietary indoor feedback thermostat connection interfaces will have a relatively small impact.

A simple industry standard in this area needs to be developed.

Gordy

@hot rod I think the reasonable system life expectancy is going to be dictated by the old equipment being replaced in the owners mind. If it lasted 30 years then that would be a basis. I think it's poor comparison to use other products such as automobiles, and such. All though we live in a throw away society, which keeps the economic wheel rolling.

I think we covered the payback in HE equipment is not what most are going to see in a high temp emitter application. When compared to same install of a CI flavor with a whole lot less maintenance, and losing a few percent on efficiency. For the love of the earth yeah. For the wallet no.



I also think a lot of the proclaimed 30% plus savings from a switch to HE comes from the right sized boiler upon replacement. Not so much the efficiency. If apples to apples the most you could see is 15% if the HE equipment was actually getting 95%.

Paul48

"If we want super simple maybe we look at gravity powered systems again".


Hmmmm.............Now that might be a proper place to use modern technology. It is what we are trying to achieve with todays mod/cons, anyway. Constant circulation, low flow, high DT. It would involve a very specific design of a mod/con. It could go seamlessly into gravity conversions and new construction. Think about the possibilities.

Gordy

Just have to get the HX to play nice.

Paul48

It would have to be a specific design. Maybe I'm missing something, but the only drawback to gravity systems was the fuel wasted with the old boilers.

Gordy

Some comfort to.

Paul48

I'm sure they were quite comfortable, self-balanced systems.

hot_rod

Paul48 said:

I'm sure they were quite comfortable, self-balanced systems.

A few drawbacks included the limit on how long of a horizontal run was possible. Also the bouyant hot water raced to the highest points in the systems and throttle valves on the upper radiators need to be adjusted for the lower levels to get sufficient heat.
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I'm curious to see how modern mod cons of whatever description you like,. low mass, mid-mass, work at extreme low flows.
I can run my tank style HTP Phoenix all day long with no flow, and I do as it generates DHW with an external plate HX.

The old high iron mass, high water content, relatively inefficient HX designs could work at essential zero flow rates.

With modern blue flame burners and thinner walled HX and burner to fluid tolerances much tighter??

Complete air elimination and clean HX surfaces will be critical to the life expectancy, perhaps.