Caleffi's Commitment to Technical Support for Our Customers
July 14, 2014

Welcome to the Ask Caleffi Blog!

Is it just me, or is good technical support hard to find these days? How do you locate - and actually talk to - the right person with the right answers? It’s tough!

We all hear a lot of promises from a lot of companies we deal with, but why don’t more of them actually do what they say they do? As Benjamin Franklin famously said, “Well done is better than well said.”  He also said, “Beer is proof that God loves us and wants us to be happy”, but that's a topic for a different day. Here at Caleffi, our tech support team - Kevin, Nick, Woody, Bob, Mike and Rex - have over 150 combined years of experience in our industry.  We are here to answer your technical support phone calls and emails.  We want to be your business partner of choice in the hydronics industry and we believe our level of experience and expertise can help us reach that goal.

In support of our dedication to your success, check out these tech support resources: 

  • → Our new Ask Caleffi blog featuring Bob “Hot Rod” Rohr, our training and education manager, and myself, Caleffi application engineering manager.  Did I mention that you can also email us at with your questions? 
  • → The popular Coffee with Caleffi™ webinar series. This don't-miss and FREE webinar series is a diamond in the rough!
  • → Short on time but need answers?  Then our YouTube video training series is just for you.
  • → Need an in-depth study guide of hydronic, plumbing and renewable energy related topics and design conventions?  Then idronics™ - our educational journal series for hydronic professionals - is the resource for you.

All these resources - at your fingertips - are designed to provide you with the answers and information you need to finish your projects on time and on budget. Our business commitment to our Representatives, Wholesalers, Engineers, Contractors and OEM partners has never been more focused.

Get to know us, we will help you grow your business!

Kevin Freidt

Blog post comments
July 14, 2014

Very nice welcome post. Good luck!

Dale Cikaluk
July 15, 2014

Just checking out the blog!!!!!!!!!!!!!!!!!

July 15, 2014

Thanks, Dale! Tell your friends!

Joe Staniford
July 24, 2014

Can you comment on the relative merits of a Geo system vs. a air to water Heat Pump eg. Daikin Altherma


In reply to by Joe Staniford

July 25, 2014

The big plus, in my mind, for air to water is not needing the wells, loop field or pond source. So that cost and logistics goes away. The designer needs to know how the air temperature, required supply temperature interface. As the ambient temperature goes down, so does the efficiency, in heating mode. At a point a backup heat strip, or heat source may need to be enabled. The designer and installer needs to be aware of those relationships. Look to idronics 9 and 14 for more number crunching

Robert Kidwell
August 02, 2014

I have an iSolar Plus as the controller for and HTP Versa Hydro System. Soon after the initial installation 16 months ago the unit appeared dead with a blank screen. There was some discussion at the time as to whether there had been some sort of 110V power surge. The fuse was replaced and it popped explosively across the room. The unit was replaced under warranty and the unit worked fine. Now 9 months later the exact scenario recurred. The house has "whole house" surge protection and the iSolar Plus has local surge protection so I don't believe the problem is with the 110V power supply. In the first instance we had two months of flawless operation and in the second case we had about 9 months. I am dead in the water as far as my solar and seriously in need of some advice. Thanks, Rob

October 23, 2018

Can I mount a HydroLink 559 reversed? Meaning boiler feed comes from the right side? Im looking at the 2+2

Please advise



November 30, 2018

Hi, I’m wondering what is the Allen plastic screw on the side of 5027 valve used for ? I’m thinking assembly of the unit. Thanks, Ed

December 03, 2018

Yes, you are correct, Ed.

March 09, 2019

I Have a doubt from long time. Why do I need only 20% flow to produce 50% cooling output....why do I need 100% flow to produce 100% output...why is this not Proportionate as I thought it to be?

Kevin Freidt

In reply to by Siva

March 19, 2019

Different valves have different "flow characteristics", for example "equal percentage" or "linear" or "quick opening". Flow versus valve position and heating or cooling output is based on the valve flow characteristic. There are many good detailed graphics and explanations on the internet, more than we should list here.

March 10, 2019

what is the physical significance of Cv of a valve? How can I eliminate different deltaT across AHu cooling coil and how can I fix it to same deltaT everywhere so that I can avoid mixing loss


In reply to by Siva

March 19, 2019

Cv is the amount of flow, in GPM, that a full open valve will pass at 1 psi differential across the valve. It has to do with the size of the flow area of the valve when full open. Your deltaT question is best referred to our technical journal series called idronics. Take a look at issue #23 "Heat Transfer in Hydronic Systems".

March 12, 2019

why DP sensor is placed across the AHU coil that to at the end of farthest coil ?


In reply to by Siva

March 19, 2019

A DP sensor placed near the end of the circuit will assure (assuming it is being used as an input to a controller which is in turn controlling a variable speed pump) that there is enough pressure differential to satisfy the flow requirements of the furthest load.