Variable speed ECM boiler pumps

SWEI

So many sidebars in so many other threads that I decided to start a new one.

Given the complete lack of small ECM circs with 0-10V inputs and with the recent discussions about using throttling valves or flowsetters on boiler circs, it occurred to me that we actually have a relatively easy way to do this:

If we use a ΔP circ for the boiler loop and install a properly-sized Belimo CCV downstream, we end up with a 0-10V input that covers whatever range we need. Or did I miss something?

bmwpowere36m3

I'm listening....

Rich_49

Can we insure maintaining the Delta T through the boiler that is used during AFUE testing procedures ?

I understood those discussions and the use of certain devices to maintain a minimum head to guarantee a minimum flow through the HX . Too low head could have us putting more fluid than we need and narrowing the Deltas through the HX .

Thinking in the long term this is a strategy that many can use without complicating too much and using off the shelf DT circs that are readily available . The last few years have been pretty illuminating and many recent presentations about alot of topics all pont to maintaining a Delta through the various parts of piping systems goes further toward reaching max efficiency than anything else we have at our disposal .

At the end of the day I think we are all just looking for some truth and a greater understanding by many as opposed to the few .

Good idea for a new discussion Kurt , hopefully it does not go south like others .

SWEI

I'm just offering a simple way to get 0-10V control using existing small pumps. With proper sizing of the CCV, we should be able to set the range so that it tracks the boiler's firing rate. VR1816 + CCV = control.

bmwpowere36m3

If the boiler is capable of 0-10V pump control... can you just hook up that 0-10V signal to the valve instead. Then set the pump delta P so you maintain min flow at full-throttle.

SWEI

Exactly.

Eastman

Does Wilo make a 0-10volt model? I see it listed as an option with some kind of add-on module.

Gordy

Don't you have to use a building management system with the 0-10 Vdc? Or is the Belimo the bridge. I did not think it was a direct plug, and play boiler to pump.

Eastman

I don't think a BMS is necessary. I thought the typical setup directly modulated the pump.

njtommy

Building management controls could be 0-10vdc, 2-20ma or 4-20ma.

Are we talking solo primary pipe pumps or system pumps. Or really both?

Really it would be nice to have it all. Reset water temp on OAT and indoor air temp.

Gordy

@njtommy yes that's the ultimate ticket.

So my question is the big V does this to an extent for a long time now. What gives? They modulate pump speed to modulation no?

Gordy

I'm just at awe that there is capability there on both sides yet a big gap to marry everything together. It seems the collective is doing the thinking, and heavy lifting in this black hole. I mean it is in the best interest of the boiler manufactors to have a nice clean package. Or at least one that's adaptive to get the most efficiency out of their product. HTP is pulling ahead.

Rich_49

Using all this extra stuff is kinda self defeating , No ? I thought the whole exercise was to be capable to build affordable systems that were less complicated but offered the best efficiency for the end user or in short , to grow the hydronics market .

Did I miss something ? One device to keep head at a point where the DT circ will not flow too much through boilers at low end is no good ? There are a few boilers now capable of not using P/S piping and accepting low flow .
Guaranteeing lowest RWTs and varying flows based on real time system feedback at a low cost is bad ? Installing many more jobs each year sucks ?
I don't get it . We beg for low cost equipment to make life easier so we can add an excessive amount of complexity that that will not help the average installer ? Will exacerbate the issues that already exist , dumb s*^&s who cannot install a boiler of the cast iron type properly .

Looking more hopeless by the minute . Nice clean packages are here and don't require polishing guys , embrace them . Dumb guys like me don't get the need for all the extra stuff . I'm just a plumber , not a magician damn it !

bmwpowere36m3

I thought it was not recommended to use a delta t pump on a p/s plumbed mod con as the boiler pump.

I know the lochivar is capable of controlling the boiler pump with a 0-10v or 2-10v signal. Even though I don't have one installed, I can see on the display the boiler is modulating the pump output in percent.

Rich_49

@bmwpowere36m3

We have been discussing the newly acquired ability to do just that with a few boilers that are capable of readily accepting flow rates down to 1 GPM . Minimum flow rates were the issue to not being able to do this in the past .

Gordy

Well,the whole idea is to get away from P/S, and the extra pump, but if your adding something else at the same, or more of a cost its self defeating which is @Rich point. Trying to wade through the crap, back to KISS.

BobC

Over the years I've learned that simple systems are the most reliable systems. I'm chary of adding complexity to a system for just a little more efficiency; that applies to any system - keep it as simple as you can.

Otherwise you may find your self joining the "Work it may, but shine it must" brigade.

Bob

Rich_49

@BobC

Keeping it simple just became getting the most efficiency . Never thought I'd see the day where I did not require 4,000.00 worth of rags . Seems it has happened though .

Imagine that , lots of folks are scared of this , what will they do ?

No , I am not referring to anyone whom has commented up to this point . rest assured though , they will soon visit .

bmwpowere36m3

It's certainly an interesting concept…. since my system/install is fairly new, I'll let it play out for a while before revisting this. Of course depending on the cost of the CCV valve and how my system works out.

I only saw 1 site listing the valve, which I think includes the actuator for 1" pipe ~$150. @SWEI is this what your refering to: http://blackhawksupply.com/products/b223-lrb24-sr

On my system with P/S and Alpha pump on its lowest speed my boiler dt remains around 5*, I've throttled it to 20-30* but as temp continue to drop I have to manually de-throttle it (already setup a ramp delay) so it doesn't trip on high boiler delta (as fire ramps up). My inlet temps have been around ~100-110* so I'm condensing well, I think.

Having a "system" to throttle that boiler pump would eliminate that "work" (messing with pump outlet iso-valve). Now whether it has any effect on "efficiency" I can't say. But in my case, since the boiler is already setup for it (minus personal labor), for $150 or so to keep the boiler condensing more… maybe there is some ROI to it.

Maybe I'm just dreaming, lol.

Heat_n_CT

15-58 on speed 3 is 87 watts, I think that's trying to be avoided with the ECM dP.

SWEI

Hatterasguy said:

What is the reason to utilize a ΔP pump?

Utilizing a standard 15-58 on speed III provides 14 GPM at 4 feet. When you throttle it with the valve, the flow rate decreases linearly all the way down to 1 GPM at just over 18 feet. This provides a huge range for the valve to operate.

I do not see the purpose of a ΔP pump which will slow its speed simultaneously with its reduced output caused by the increasing head from the valve.

The ΔP ECM pump is inexpensive and widely available. No reason the conventional PSC pump couldn't also take advantage of a properly sized CCV.

In answer to to an earlier question, the intent here is rather basic: Allow currently available boilers equipped with boiler circ speed control outputs to control the speed of the circulator that serves them.

njtommy

@Gordy
In most commercial stuff I see pumps are set for DP or DT depending on building design.
Boilers for higher efficiency are reset to supply water depending on our door air.
I'm not sure if I've seen the pumps set up any other way with VFDs on them.

CI boilers and Cleaver Brooks boilers may just cycle or and off. Or hang on low fire. All day depending on how cold it is out side.
Even our high pressure steam to water tube bundles get reset on OAT.

njtommy

The biggest problem with 0-10vdc is going to be calibration of firing rates and flow rates to get every thing to work together.
Just cause you telling the boiler to run at 1-2vdc doesn't mean your pumps flow rate at 1-2vdc is good for your system. The water coming back to your boiler maybe too cold and not able to heat the space with little flow.
You need to be able to set your minimal flow requirements to the system and that would be your lowest vdc input to the pump.

Again on larger scale our min pump speed is round 20-30% do to lubrication of bearings.

SWEI

I've actually done just that with cascaded commercial boilers. We set minimum and maximum speeds on the pump so they made flows appropriate to minimum and maximum firing rate. Boiler ΔT tracked surprisingly well.

Gordy

I don't think adding a couple hundred dollar valve to a system that uses very little energy compared to that extra pump to eliminate the guy in the mechanical room throttling valves through out the season is a deal breaker. Or you could get the little guy that turns the light off in the refrigerator.


What delta P controling delta t can offer is a little wider selection of circs. Let's face it the 2218 is not for all systems.

Or the Belimo energy valve, but that is self contained, but then so is the 2218. A bit more pricey.

Harvey Ramer

I have different thoughts on this. The boiler fire rate should be controlled by the building's heat demand, not water temp.

Imagine a system with TRVs for every room, delta-p pump and a flow meter with a 0 to 10v output.

Or a system with both indoor and outdoor sensor feedback and a computer algarithm to calculate firing rate rather than calculating supply temp target. Of course in a multi-zone system, one would want proportional flow control to the respective zones.

In either of these, the boiler could be kept from firing until the load provided for a minimum run time at low fire.

I guarantee it would be the most comfortable and effecient way of doing things.

Gordy

If you keep the boiler from providing btus to the space until a minimum run time is reached. Will you not sacrifice comfort? Something has to give.

Harvey Ramer

No, you keep in from coming on until a minimum run time is met at low fire.

Gordy

Maybe I'm miss understanding not uncommon. So boiler is off. There is a call for heat, but it's not enough of a load to let the boiler operate for an efficient period of time at low fire. Will what ever zone that is waiting for that optimum parameter not still be losing set point?

Eastman

How do common boilers capable of direct pump modulation decide how to modulate the pump?

Harvey Ramer

Each zone is proportional. Each zone has temp feedback in hundredth of degrees. The control looks at each sensor and based on the actual temp, speed of decline, predicted speed of future decline based on outdoor temp, and uses these readings to determine boiler operation. Each zone has the flow proportionally controlled and whenever the boiler is on, all zones will get some btu input.

hot_rod

SWEI said:

So many sidebars in so many other threads that I decided to start a new one.

Given the complete lack of small ECM circs with 0-10V inputs and with the recent discussions about using throttling valves or flowsetters on boiler circs, it occurred to me that we actually have a relatively easy way to do this:

If we use a ΔP circ for the boiler loop and install a properly-sized Belimo CCV downstream, we end up with a 0-10V input that covers whatever range we need. Or did I miss something?

I think you will see a movement away from the "old school' analog signals 2- 10VDC and 4-20ma. Already most of the Euro pumps, solar and building and heating controls are moving to a true digital signal PWM. The issue with interference goes away with digital signals, I'm told. And you can easily bring in derivative in addition to the "P" i.e.. PI and PID. this is critical if you goal is ultimate "system efficiency"
After all there is a reason they limit the low end of those analog signals to start at 2 and 4.

Of course the Knuever boys of tekmar Germany and tekmar Canada knew this years ago and introduced the US control market to PWM and taught us about all the P's P, PI, and PID and the value of them, from day one with their controls.

The same with PICCV valves. They offers much more functionality and adjustability than a circulator controlled by just temperature input from relatively slow thermistors.

I'm not sure how a CCV or PICCV and a ∆T circ would get along together as the two algorithms may bump heads, just as mod cons and ODR may with ∆T pumping. Have you tried this Kurt?

With modern "engineered" actuators the PICCV can move amazingly fast, and nail exact control with virtually no lag or delayed response. The two together may spend a lot of time "in the weeds" hunting for one another? I believe Steve of Taco already alluded to this challenge.

SWEI

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.

My intent with this thread was to point out that we can relatively inexpensively create a 0-10V controlled circulator by pairing a CCV with a currently available ΔP pump. I'd much rather have some kind of addressable digital interface -- ideally one that could manage multiple circs, but AFAIK we don't have that option available to us in North America (yet.)

Gordy

Well i don't think you missed anything Kurt. In any given system delta p, and delta t should be predictable whether you use a delta p circ, and a throttling valve to get a given delt t, or use a delta t circ, and a throttling valve to force a delta t. Except it's not a manual adjustment with your idea.

SWEI

The system ΔT stays relatively constant when the ODR is properly tuned (as ISTR you mentioning in some earlier post.)

This stuff works well enough that we can hold most rooms to within half a degree of setpoint. Improvement efforts now focus on other things.

Paul48

I believe Taco's whole "00" series are available as VV.

Gordy

I think the right amount of emitter saturation, and type says huge amounts about an inherently stable delta through out a wide range of system loads with out intervention. The more the better, or more stable.

Gordy

It is,at quite a price compared to a delta p circ. All though by the time you throw a delta p, and a Belimo CCV together your a bit more depending on size valve, but I think using the Belimo setup opens many doors to circ sizes even outside tacos 00 vv selection. The Belimo valve is doing the work.

Gordy

It also all depends what setup we are talking. Piping direct, LLH, single zone multiple zoning etc.

hot_rod

SWEI said:

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.

My intent with this thread was to point out that we can relatively inexpensively create a 0-10V controlled circulator by pairing a CCV with a currently available ΔP pump. I'd much rather have some kind of addressable digital interface -- ideally one that could manage multiple circs, but AFAIK we don't have that option available to us in North America (yet.)

The "PI" part of the valve makes it work just fine with fixed speed circs, although ∆P ECM circs are better yet for reducing electrical consumption. And the first "C" is something Robert Bean Esq. has been trying to pound into our heads for about 30 years now.
Pressure indépendant characterized control valves.

It's really tough to get that control-ability with butterfly or non characterized ball type valves.

I wonder if the Belimo valve will be certified to the upcoming BTU metering standard so it could be a billing device also.

njtommy

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