Heating Help

Opinion from a Pump Guy

@ January 4, 2012 12:25 PM in Pump to or From modcon

At the risk of stirring the pot, here's my take on this...

A lot of mod con boilers are using low mass, high pressure drop heat exchangers.  These definitely require minimum flows to stop boiling, satisfy low flow/no water safety devices and keep the HX from internally fowling up.

Typically (and I recommend this) there is usually a dedicated boiler pump (shunt pump) for each boiler, sized to overcome the head loss and BTU rating pf the boiler.  Similar to copper tube boilers, manufacturers suggest pumping into the boiler to insure proper flow through the boiler.  Yes, I know water is not compressible but it does take the path of least resistance.  And yes, this does not fit into the "pumping away" idea.

But, if the circ is only sized for the boiler head loss and flow requirements, then an additional primary loop circ will probably be required anyway (especially with multiple mod cons).  Yes, even with hydraulic separators in the system.  The primary loop circ and related stuff (expansion tanks, purgers etc) can be installed to "pump away".  In addition, the primary loop pump can be controlled to provide the right delta T or to reduce return water temperature to assist condensing.

As long as the shunt pump is not over sized I can't see how it would cause a relief valve to blow unless it was deadheaded.  If the system pressure is that close to the set pressure of the relief valve to cause it to blow when pumping into the boiler than the relief valve would have to be replaced with a higher pressure type (keeping in mind not to exceed the pressure rating of the HX).  Consult the boiler mgf!!!

One more point, turbulent flow is required for the geothermal guys.  Hydronic heating uses laminar flows - turbulent flow in radiant actually potentially can reduce the heat output of heat emmiters - this is why hydronic rule of thumb is 4 to 4.5 feet/sec water velocity.

Hope this helps guys.  For those that pump away from mod cons with no problems, if it ain't broken, don't fix it as the saying goes.  It will probably work either way...

Pumping Backwards

@ December 21, 2011 1:53 PM in Just for fun, pumping backward

Interesting concept - but...

First, I am assuming the discharge of both pumps are facing each other with at least 6 pipe diameters of straight pipe between them :-)...  I see two potential issues with this (one real nasty).  BTW, these issues are standard and ECM circs.

First, the loss through the off pump will be substantial (but I have no idea how much - us pump guys do not test for this and it would depend on the size, age, type of the pump).  Remember, the water would have to enter the outside blade area of the impeller, turn 90 deg and make it's way to the impeller eye, and then turn another 90 deg to make out the inlet.

Second (and this this is the biggee), there is better than a 50% chance that the off pump (circ) will run in reverse direction (depends on the relationship of the throat of the volute and the impeller vanes).  When an off pump runs backwards, depending on the type of pump and motor, it can change the motor into a generator.  Or, if the impeller is threaded on the pump shaft it could become loose and possibly spin off.  Lastly, if a pump is spinning backwards and is powered up real nasty things can happen (shaft breakage, overloads).

You can try it but centrifugal pumps are not designed for this application - I can't speak for the other guys but I would have a real tough time warrantying a failed pumps (circ) installed facing each other.

ECM vs Standard Circs

@ December 20, 2011 5:33 PM in Wilo Stratus with TRVs

Furnacefighter - I have to tell you your Wallie name is excellent.  I had Dan over to WILO years ago and he quickly pointed out our biggest competitor in the USA are the forced air guys.  Never a more accurate statement said!  But on to the explanation of ECM...

A standard circ will increase it's differential head as the flow decreases (trade off, less flow more head and visa versa).  That's why it tough to keep zone valves lasting and controlling heat in shoulder heating seasons.  And it causes noise when the last zones are trying to close (unless there is an energy using by-pass).

ECM pumps have a permanent magnet rotor.  The software in the brain (VFD) sees the relationship between the spinning magnetic field of the rotor and the motor stator.  When a valve in the system opens or closes the circ sees the pressure "push back" or change on the discharge of the pump, sees a change in the rotor/stator magnetic field relationship and adjusts it's speed and differential head based on the setting of the circ's control logic.

Differential Pressure Variant (Delta PV) is simply the relationship between max speed and dead heading.  When an ECM circ is set at say 12 feet, that means it's 12' at max speed and exactly half of that at zero flow (6').  This is referred to as an inclining performance curve - less flow, less differential head - the opposite of a constant speed circ.  Remember, a friction loss curve is inclining as well - and overcoming friction loss is all a circ is there for (while providing flow).

And, you are correct, variable flow circs are not recommended for mono-flo systems.  They are constant flow and require the right water velocity across the tees for them to work.

ECM Pumps With TRV Systems

@ December 19, 2011 10:58 AM in Wilo Stratus with TRVs

Interesting question.  In reality, an ECM circ wouldn't "see" a TRV any differently than a typical zone valve.

Deadheading is no problem due the Delta PV control strategy (lower differential head at dead head vs max speed).  This control actually tries to track a system curve, reducing differential head as flow and friction loss decreases.

The ECO has a max wattage of 59 Watts at full speed and 5.8 at zero flow.  Deadheading a constant speed circ is a heat issue (especially a wet rotor).  I can assure you there is no heat generated at 5.8 watts.

One other "interesting" thing to consider...  On "non-radiant" systems with TRV's and system setback what happens to the TRV's when the system fluid temp is lowered by system setback (if there is one)?  They will likely open - causing an overall system flow increase and more power to be used by a standard circ.  ECM circs have an user selectable "pump setback" feature -  when the pump "sees" a system setback it will run at min speed, automatically returning to normal operation when the system returns to normal operation or there is a call for heat during system setback.

Difficult to explain but way cool non the less...

Web Seminars

@ December 16, 2011 10:20 PM in A question for everyone

Dan , I have been running free, one hour Webinars for the last 8 months using GoToTraining.  The annual subscription is about $2,400 for unlimited sessions of up to 200 attendees

It works really well - I do a pre-test, the program allows for up and down loading tec docs and PowerPoint Presentations - plus the sessions are recorded for viewing after the session.  Typically I get about 80 to 100 attendees every week.

The good news is the folks that attend really like not having to invest the time and money to travel.  Plus it's great considering all the product launches I have done - hard to keep up.

The bad news is it has really hurt the attendance in our Chicago and Thomasville training sessions (nice to train face to face).  Also, you will never get 100% buy in on the best time and day of the week.

I would highly recommend you do some on line training - let me know if you have any questions or are looking for suggestions...

And to all you wallies, have a great Christmas and all the best for 2012 (hope to see you all at AHR in January - like Dan says, hug your kids (and in my case grand kids!

If any of you want to be included in my future web sessions, drop me an E Mail at steve.thompson@wilo-usa.com

Stratos or Magna Minimuim Boiler Size

@ November 28, 2011 12:27 AM in Pump speed control - How do you guys do it?

I noticed a statement "even the smaller models of those (Stratos and Magna) are massively over-sized for pretty much anything under about 500 MBTU/h".

Sorry to say that is not true.  The Stratos 1.25 3 x 20 (our smallest of 10 models) maximum head is delivered from zero to 12 USGPM (up to 120,000 BTU @ 20 deg delta T).  Wattage range is from 9 to 85 watts.

So (and I hope this does not sound like a sales pitch) it can handle even the smallest boilers.  Just wanted to clarify this...

IFC Circulators vs Flo Checks

@ November 22, 2011 12:36 AM in IFC pumps

You asked...

Back before us pump guys put checks in circs our industry installed a flow check (spring loaded check valve) on the return line.

My opinion, the old way was the right way.  Having a check valve installed immediately after the impeller, the most turbulent flow area, is technically not correct.  Theoretically there should be as much as 8 pipe diameters of straight pipe on the outlet of a pump or circ.  And how do you bleed air between the circ and check valve when installed vertically?  And what happens if the check valve plugs up when it's installed in the pump volute?  And what if the circ with the IFC is replaced with one that does not have a built in check?

Ya,I know it is rare any of these issues occur and there are a pile of IFC circs installed and are working OK.  And the installation cost (materials and labor) are less when IFC circs are used - but...

PWM Circs

@ November 21, 2011 10:54 AM in Pump speed control - How do you guys do it?

Here's the deal...

Pulse Width Modulation simply means modulating the width of the electrical sine wave by "chopping" the sine wave of the power to the motor.

It is either done externally (Tekmar have been doing this for years - with injection circs) or via an integrated circ controller.  Most (I think all) small, standard "non-ECM" circs from all manufacturers can run on PWM (WILO for sure)

To be honest, I am not a huge fan of PWM as below 30% capacity the circs's life is shortened and they have a tendency to get noisy.  But back in the old days that was the most (and only) way to vary the flow in these little guys.

Pump Speed Control

@ November 4, 2011 4:07 PM in Pump speed control - How do you guys do it?

Couple of thoughts on this...

Assuming the application is a "shunt" or circ dicated to an individual boiler (this combination supplies BTU's into the primary circuit that has it's own pump), although we have a lot of ECM pumps installed in this manner working fine I have wondered if there is a concern that the boiler and shunt pump have seperate brains.  However, it makes sence that if there is an increased demand the boiler's firing rate goes up and, due to the increased demand the pump speeds up at the same time.  To date we have not had any complaints with ECM on Mod Con boilers (after 4 years of selling these in the USA).

Technically speaking, probably best to use a boiler control with a PWM output and modulate the pump flow with the boiler firing rate.  Delta T is a "it depends" question.  Is there outdoor reset?  What effects the boiler firing rate?  Is it a high friction loss heat exchanger?

Today there are a number of larger boilers that use a modulating gas valve that has a 0-10Vdc signal modulating the combustion air fan - and this same signal can modulate the RPM of an ECM pump - waaaay cool.  500,000 BTU is 50 GPM, modulate down to 100,000 BTU is 10 GPM - extremely simple control.

Looking at the primary loop, what we have found is for condensing apps, control the return water temp to assist condensing (and of course the opposite for non-condensing boilers).  Adjust the speed of the BTU train (thanks Dan - this is a great analogy).  But again this can be an "it depends" answer (for example, is there a hydraulic seperator in the system?).

Regarding system pumps, delta T only works if each zone is relatively the same size (this is why differential pressure control is by far more common).

Hope this helps...  It's not overly complicated actually - mostly common sence.

Combining Radiant Floor with Hydro Air

@ November 1, 2011 12:57 PM in Combining Radiant Floor with Hydro Air

Radiant in a basement is awesome - at least 20% more efficient than blowing down hot air from a ducted system, vastly improved comfort (warm floors), no wasted space for ducts and quieter.  I would also suggest the basement would be drier (less chance of mould formation).  OK, let's throw in a couple of hot water towel warmers too (my opinion an often overlooked option of HW heating over forced air).

I looked for application drawings for combo systems but unfortunately all I could find was radiant panel/re-heat fan coil/indirect DHW system drawing (by Siggy).  Note this system is designed around an ECM circ - if you use a constant speed circ you might want to consider by-pass loop and wiring a control circuit to shut the circ off if no flow demand (this stuff is NOT required with ECM circs).  Caution on temps and boiler types - radiant is low temp, hydro air might be high temp (or higher temp than the radiant) and the boiler type will have say in it's temp as well (condensing vs non-condensing).

The system drawing is attached (I have others if any of you Wallies want).

ROI ECM vs Standard and Performance Ratings

@ September 29, 2011 5:47 PM in Now I see why the Grundfos person posted the video on You Tube.........

Here's the deal regarding electrical savings and pay back - IT DEPENDS!

A standard wet rotor pocket circ runs at about 100 watts (real wattage measured with a watt meter - the wattage we pay for).

ECM runs at an average of 15 to 20 watts (max is 58, min is 6).  Reason this is not midway between is 99.9% of our systems are over sized and they run partial load at least 40% of the time (this is where load profiles come into play).  Let's use 20 watts to be fair.

Difference is of course 80 watts.  Times 4,320 hours (6 months @ 24 hours/day) is 345,600 watt hours or 345.6 kWh. Times $0.14/kw is $48.39 annual savings.  Payback varies based on region, based on sell prices.  This would involve a discussion on pricing - I am not going to open up that can of worms.  However, rule of thumb is ECM is 2.5 to 3 times more dough.  Safe to say payback is less than 4 years.

Scenario 2:  8 month season, pump is operated of a relay panel so only runs 6 hours/day.  Cost of electricity is $0.09/kWh.  8 x 30 x 6 = 1,440 hours. 1,440 x 80 x 0.09/1,000 = $10.37 annual savings.  Payback based on power consumption only is a very long time.

Scenario 3:  5 zone system using five 100 watt zone pumps.  Replace with zone valves and one ECM pump.  No, I ain't doing the math but I am sure you get the drift (brand X zone valve is 0.9 amps at 24 volts or 21.6 watts).  The wattage of a larger ECM pump to replace the five 100 watt pumps would average 80 to 100 watts max (total, not times 5).

Note:  Payback considerations should also include the install.  ECM means no by-pass and no control wiring/relay/transformer back to the pump required.

Last point, when using ECM on a primary loop think about better flow control, lower return water temp so a condensing boiler might even start to condense - how cool is that?

Reply to Bill Clinton

@ September 28, 2011 9:04 PM in Now I see why the Grundfos person posted the video on You Tube.........

You are very welcome Bill.

I've got to tell you, after 37 years in the pump business (sold them all) this ECM, sensor-less, variable flow "smart pump" technology is waaay cool.  As far as innovation goes I rate it up there with condensing boilers, radiant pipe with oxygen barrier and good outdoor reset and multiple staging boiler controls.  Honestly - no bias...

There must be something to it - all manufacturers will have this some day.  We (the pump industry) needs to keep it reliable (as you mentioned) and simple (like our one page quick start manual).

We have distribution all over USA and Canada now - let me know where you are located and I would be happy to give you some distributor names in your area.

One thing new we recently did with our ECO was to add a check valve and rotating flanges to enable you to replace brand X or brand Y (which, by the way are very good at what they do, make great products and are formidable competitors).

I appreciate your honesty - you calls em like you sees em!  Good luck this heating season - hope it's as cold as hell so we all sell lots of equipment!

Responce to Bill

@ September 28, 2011 10:32 AM in Now I see why the Grundfos person posted the video on You Tube.........

Bill, good questions/observations for sure.  Regarding reliability:

- ECM technology is based on using permanent magnet rotors
- PM rotors have 3 to 4 times more starting torque than a std wet rotor circ (tested and proven)
- PM pumps are soft start and run substantially cooler than standard wet rotor pumps, less heat less typically translates to longer life.
- As ECM pumps lower head as flow/system loads goes decrease they are less stressed than a constant speed circ at low flows (think of slowing your car down by keeping your foot on the gas and hammering on the brake)

End result is our % failure rate on the ECO and Stratos is actually much lower than our standard pumps (that are running at less than 1/2 of 1%).  This is the main reason we increased our warranty to three years a while ago (of course I can't speak for Grundfos and B & G but I would assume they are seeing similar results).

We all could argue (discuss is a better word) the energy and cost savings - I have attached a independent analysis done by an engineering group up in Canada a few years ago.  Granted it is a commercial project but it does show real world stuff.

Power Consumption Based on Load Profiles

@ September 26, 2011 6:52 PM in Now I see why the Grundfos person posted the video on You Tube.........

Our WILO selection software calculates annual electrical costs, based on a typical system load profile.  These load profiles are very close to being consistent in all heating areas on the planet, the only variant is the number of operating hours.

Running a system 5500 hours annually, at 0.14/kWh the cost to run one circ at 10 USGPM and 7' of head ranges from $70.45 for a standard circ (WILO brand) to $11.95 for ECM (10 USGPM is approx 100,000 BTU) per yer.

Same data, but 30 USGPM and 20' of head ranges from $332.27 to $60.13 per year.

I have attached a word doc with this information.  The software does not take into account the effects of using fewer pumps, eliminating by-pass valves, overall system energy savings, the effects of condensing boilers actually condensing and so on.

Adding Zone 7 with ECM Delta PV pumps

@ August 8, 2011 12:27 PM in Wilo capacity-adding zone 7

Good question.

Assuming the system with 6 zones was working OK I doubt if adding a 7th zone would cause any issues (unless it's a huge zone).  The way Delta PV works is if there is more places the water can go (like a 7th zone) the pump will automatically increase it's differential pressure (and consequently increase it's flow).

If you were using a manual 3 speed pump most likely you would have to change speeds.

Pump Training Materials

@ May 13, 2011 3:37 PM in Circulator question

Mark, send me an E mail with your mailing address.  I will be happy to send out our training information (systems, pumps - the whole deal).

And feel free to use in your classes!

Delta P Across a Circulator

@ May 13, 2011 10:04 AM in Circulator question

Guys, I must be missing something here.

The pressure differential across a circ (pump), or delta P, or boost pressure (whatever you want to call it) on a closed loop system is based on the pump's performance curve and it is the pressure where the system curve intersects the pump's performance curve.

And, this "boost pressure" needs only to be high enough to overcome the circuit friction loss at the flow.  A 007 providing 2 PSI differential pressure (x 2.31 to convert to feet of head) will provide about 18 USGPM flow (enough flow for a 180,000 BTU load at 20 deg F temp differential.

Even if the Taco 007 was dead headed (run at zero USGPM) the differential head (or shut off head) is 10.5 feet or 4.5 PSI.

I don't know where the expected 8 PSI differential comes from.  Remember, the expansion tank is only there to compensate for the expansion and contraction of the system fluid as it's temperature changes (that's why it's called a thermal expansion tank) and 100% for sure has to be on the inlet side of the pump.

Hydraulic Institute Looking for System Savings Examples for Industry Awareness

@ May 10, 2011 2:39 PM in Hydraulic Institute Looking for System Savings Examples for Industry Awareness

Fellow Wallies, I need help on this one...

The Hydraulic Institute is looking for overall SYSTEM energy saving examples (heating or cooling) where a pump retrofit was performed.  I have a lot of documentation and case studies on pump electrical savings but very little on overall system material.  This is required for various reasons including an HI Systems Standard and the HI Utility Rebate Task Team.

Do any of you have this information or where I can look?  This is way up there on the importance scale - any help would be very much appreciated...

More information on the Hydraulic Institute can be found at the following links:
http://www.pumps.org/
http://www.pumpsystemsmatter.org/default.aspx

Short Cycling Boilers - Would ECM Pumps Help?

@ April 22, 2011 12:40 PM in short cycling in shoulder season, fact/fiction/improper design ?

Curiosity killed the cat...

Reading this post I am wondering the effect of a variable flow ECM pump during shoulder season heat loads (the toughest time to maintain comfort in my opinion).

In theory, boilers with excessive flow rates cycle more - makes sense that they cycle less with lower "proper" flows - one of the benefits of ECM pumps.

Do any of you have a project that was converted from constant speed circs to variable flow and a comparison of cycling times during shoulder seasons?  I would think ECM (variable flow) would reduce cycling but don't like to assume anything when it comes to heating.

Animations

@ April 6, 2011 4:33 PM in Looking for heating system animations.

I have a couple of mod con boiler animations that are pretty cool and animations of Statos and ECO pumps that show the flow effects of zones opening and closing.

Would this help?

News from ISH - fuel cost

@ March 14, 2011 6:06 AM in News from ISH - fuel cost

Starts tomorrow.

First thing I noticed, cost per litre for gas is 1.69 Euros/litre.  Converts to $8.94/gal!  Ouch.

ISH 2011

@ March 8, 2011 10:03 AM in ISH 2011

Well, it's that time of the year (man, it's flying by!).

Next week is ISH in Frankfurt - for those of you fortunate enough to be attending this world class event, feel free to stop by the WILO booth (building 9, hall 9.1, booth 46 B, C, D).  I'll be working the booth again from Tuesday to Friday inclusive. 
Drop by our reception area and have me paged for a personal tour (and beer of course!).  I'll go through our new innovations for Germany (in preparation for the new 2013 EUp) and new innovations for North America.  Some pretty cool stuff I can assure you.

Hope to see you there...