Industry Blogs

Zone valves and indirect water heaters? I’m guessing most guys would rather drink warm beer than install an indirect with a zone valve. Why? The answers given are usually the standard ones given about zone valves in general, slow recovery, not enough flow, bad practice, no DHW if circulator pump fails but in reality the real answer is the same as it most often is in this industry, “We always do it that way” I felt that way myself, but over the course of years I ran across many jobs with a zone valve on the indirect and, by and large, the customers weren’t complaining. I assumed they thought the reduced performance was normal so I asked them and they proceeded to tell me how long their teenage daughters were in the shower and how happy they were with their decision to buy an indirect. How can this be? After doing a little research, I decided to switch sides!

We install indirects with zone valves quite frequently and never have an issue. It’s a bit of a long explanation involving a fair bit of math but bear with me. Let’s assume we are installing a new boiler with  an indirect utilizing a zone valve. How do you size a pump for an indirect currently? To do it correctly you need to know the head loss of the piping, fittings and heat exchanger as well as the desired flow rate and then choose a pump that will meet the GPM requirements at the head loss of the system. How many people do that? Usually not too many! Most people will choose a 007 or to be on “safe side” a 3-speed pump so they can turn it up. If a pump manufacturer came out with a pump that had four speeds they could be like Spinal Tap!

For an example, lets use a popular 32-gallon indirect with a head loss of 1.9ft and a recommended flow rate of 8 GPM to achieve it’s rated first hour output of 165GPH at a temp rise of 77 F assuming a boiler temperature of 180F. What’s the head loss of the piping? The short formula which works pretty well is as follows.

    Total Linear Length x .06 = ft of head

There is approximately 4 feet of head per 100 feet of pipe run, 50% is added to account for fittings which gives us .06. But what about higher resistance devices installed in the piping, like flow valves and zone valves? These have to be accounted for separately and are rated by Cv. What the heck is Cv?

The Cv rating represents that amount of flow needed in order to create a pressure drop of 1PSI, or 2.31 feet of head, across a component like a valve. How do you convert Cv to feet of head? More math, unfortunately!

    (Flow in GPM divided by Cv)2 x 2.31 =  head loss

Lets use a zone valve with a Cv of 8 in our hypothetical installation, the higher the Cv number the less resistance to flow.

   (8 divided by 8) squared = 1 x 2.31  =  2.31 ft/head loss for zone valve

What about the piping? Lets assume we have 25 feet of piping from the boiler to indirect and back. Just a little more math.  25 times .06= 1.2 ft/head

Lets add it all up!

Indirect- 1.9ft

Piping- 1.2 ft

Zone valve 2.3 ft  for a total of  5.34 ft/head at 8 GPM. What size pump do we use? Taking a look at a pump curve chart  for a circulator that will provide 8 GPM at 5.5 ft/head, a 005  is pretty close but a 007 is a better choice.

What if we used a circulator and weighted flow valve on this job? Everything else would stay the same all we would have to do is swap out the head loss of the zone valve for the flow valve. What is the Cv of a weighted flow valve? A 1” NPT flow valve has a Cv of 6.7, the same valve in sweat is 7.7 Cv.  Remember, the higher the Cv the less resistance. The installation with a flow valve actually has a greater head loss than the zone valve job? Yes, it does!

This is how we can use zone valves on indirect water heaters with no homeowner complaints The caveat when using a zone valve on an indirect is domestic priority. Without priority you need to size the circulator for the zone with the largest head loss, which may not be the indirect zone and the flow rate for the all the zones combined.

Robert C. OBrien is the owner of Technical Heating Co. LLC in Mt. Sinai, NY. Robert serves as the Vice President of the national OESP chapter. See more from Robert in his blog “Boiler Sizing & Indirect Water Heaters” “Heat Loss Calculation on every residential boiler replacement?” & “Converting from Oil to Natural Gas.”

What??? I hear this often. How about “It gets too cold here for OD reset”. Or even “I love OD reset, but I don’t understand how to adjust it.” Maybe even “I always get complaints from my customers that “the radiation is not hot enough since the new boiler went in” and one more, “It doesn’t work with this type of system”.

So, let me ask you what kind of hot water system you know of where outdoor reset will not work? I’ll answer this with one word…..None.

OD reset works with all types of hot water systems. But anyway, a quick review; what benefit does OD reset provide? It saves fuel and creates higher comfort levels in the building, not to mention reducing short cycles. It does so by changing the system’s supply water temperature depending on the current outdoor conditions. A few things come into play here: heat loss of the home (size and level of insulation), radiation (type and quantity), and of course, climate.

Those of you who’ve attended one of my seminars know that I’m a big proponent of reducing fuel bills by optimizing boiler and system efficiency. How do we do that? Proper boiler sizing and OD reset.

I believe that not using outdoor reset at every opportunity is doing a dis-service to your customers. US Boiler includes outdoor reset on our high efficiency modulation/condensing boilers, and we even offer it in a wireless version now. We even offer optional OD reset cards that simply plug into most of our cast iron boiler control systems. In fact, to achieve maximum efficiency of a condensing boiler, you must use OD reset. The lower the water temperature, the higher the boiler efficiency.

But, back to the misconception that there are applications where outdoor reset doesn’t work. Let’s touch on the different system types and utilizing OD reset. I’ll discuss four basic types of systems: radiant floors, cast iron radiation, copper fin-tube baseboard and hydro-air.

But before we get into it, let’s take a quick look at the default factory ODR settings on our boilers:

1. Low OD air temperature – 0°F
2. High OD air temperature – 70°F
3. Low boiler temperature – 110°F
4. High boiler temperature – 180°F
5. Minimum water temperature – 130°F

Radiant floors are installed in numerous ways. There’s staple-up, where the tubing is fastened to the underside of the sub-floor with or without heat transfer plates. Sometimes tubing is installed above the subfloor, with a lightweight gypcrete pour overtop the tubing. Or it can be installed above the subfloor in grooves, with flooring installed on top of it without a gypcrete pour. And of course, tubing can be installed under a concrete slab.

To maintain setpoint temperature, all of these systems will require different temperatures. The more mass and insulation below the tubing, the lower the required water temperature. And, with outdoor reset, all of these applications will provide efficient boiler operation. We could easily see water temperatures as low as 80°F or as high as 160°F. You may have to change the low boiler temperature, minimum water temperature and possibly the high boiler temperature depending on the specific application.

The folks that say they don’t need ODR on a radiant system claim that the slab’s thermal mass is enough to flywheel the system through outdoor temperature swings, and that the slab doesn’t respond quickly enough to make a difference, even with fluctuating supply water temperatures. It’s true that a radiant system doesn’t respond as quickly as copper fin-tube, for example, and yes, the thermal mass of the slab will hold a more constant room temperature.

But those are both comfort considerations, and while they’re important, they completely overlook the fact that even with an in-slab system, if the water temperature is too high, the boiler will be short cycling and burning more fuel than needed.

Keep in mind, because radiant systems are lower temperature by nature, you might need to change the default ADR settings

Cast iron radiation, contrary to popular belief, is low-temperature heating, especially in modern homes. Sure back in the heyday of standing cast iron radiators, they might have needed 170 degree water. With single pane, wooden frame windows and zero insulation in the walls and ceilings, homes had HUGE heat loads. Now, insulate that same house and install new windows, and what do you have? Probably about half the heat load, at most. But the cast iron radiators haven’t shrunk, so you’ll be overheating the home or short-cycling the boiler. Probably both…. Unless of course there was a way to drop the water temperature…. Ahhhh. Yes. Outdoor reset control.

I’ve been asked many times about what water temperature a cast iron systems requires. My answer is always the same: “That depends”. There’s a lot of mass and high water volume, so, if it’s an insulated home, the temperature likely doesn’t need to be very high. Despite that, I’ve seen plenty of cast iron jobs where none of the boiler settings were changed from factory settings.

In most cast iron applications where home has some insulation, I usually like to see the low boiler temperature, minimum water temperature, and possibly the high boiler temperature reduced. Do the homework. Do a heat loss, calculate the water temperature required at design temperature with the amount of installed radiation. Once you have your design water temp, change the OD design temperature to 60°F on the heat loss and calculate the minimum water temperature. You may be really surprised. See the feature article this month for an Alpine installed in a cast iron radiation system. Cast iron radiators and stainless steel boilers work together beautifully, as long as outdoor rest is installed and properly adjusted.

Copper fin-tube baseboard, when connected to a high-efficiency boiler, means that OD reset is a must. Not only is copper baseboard a very responsive system, but the supply temperature needed will vary greatly depending on the ratio of baseboard to heat loss. Some systems can actually operate with supply temperatures under 180°F when it’s below 0°F outside.

I know of a baseboard job is Andover, Mass., with a high limit of 163°F. Despite the bitter cold spells we’ve seen in the past two years, the temperature has never needed to be raised. He’s running a minimum boiler temperature at 120°F instead of 130°F, and a low boiler water temperature of 100°F. Outdoor reset changes the supply temperature accordingly, and the home is always comfortable.

There are still folks out there who think condensing boilers should never be used with fin-tube baseboard, because these systems require high water temperatures. It’s true that fin-tube does require, on average, higher water temps than other systems. But it’s really only at design temperatures where a mod/con boiler wouldn’t condense. For the other 99% percent of the heating season, with an OD reset installed, the boiler will run at maximum efficiency. Fin-tube and condensing boilers go together like peas and carrots, but only with outdoor reset.

Hydro-air might just have the most misconceptions surrounding it. And that’s understandable, because bringing air movement into the equation does tend to make it a bit more difficult for wet-heads like us. But one thing is for certain, you can lower the supply water temperature to your coils when the outdoor temperature gets milder.

Don’t believe me? We’ve kept tabs on a few hydro-air jobs, and next month we’ll talk all about it.

Ron Beck is the outside Technical Advisor and manager of Training for U.S. Boiler Company, where he’s been since 1998. Ron’s 38 years of experience in the heating industry include climbing the ranks of a HVAC company, from apprentice to service manager. Ron writes contributes “Beck Tips” for the US Boiler Report. Beck Tips consist of a lot of helpful technical advice for installing hydronic systems (proper boiler sizing, piping, etc).

Joe Parsons is a dedicated geothermal professional. His years of industry efforts testify of his passion for geothermal heat pump (GHP) implementation. He was voted Chairman of the Geothermal Exchange Organization (GEO) on April 20^th, 2016. Here’s a little information on Joe’s company, EarthLinked:

Joe Parsons, right, stands with his crew.

At a recent visit to the EarthLinked Facility in Lakeland, Fla., I had the opportunity to see some remarkable advancements in “refrigerant based geothermal applications,” sometimes referred to as direct exchange (DX) GHPs. In the book, Geothermal HVAC, Green Heating and Cooling, (educational textbook published by McGraw-Hill Professional in October, 2010, ISBN 0071746102 / 9780071746106), the technology is cited on pp 52-53 as follows:

“Direct expansion (DX) geothermal systems are gaining in popularity throughout the industry and the world, in large part because of their high efficiency, ease of installation, and low maintenance. They work under the same principle as the water-to-air heat pumps, but instead of using water as a primary loop for heat transfer, these systems use copper lines installed in the earth and filled with refrigerant, such as R-410A. R-410A does not damage the ozone layer, unlike many past refrigerants, although it does have the potential to be a greenhouse gas that is much more potent than carbon dioxide.

DX systems require less excavation to install. Theoretically, speaking from a thermodynamic perspective, they are more efficient because one step of the heat exchange process is removed…”

DX geo systems use copper lines installed in the earth and filled with refrigerant, such as R-410A

The facts are clear; the technology has the potential to increase energy efficiency and reduce first cost. Jeff Miller, President of EarthLinked said that he believes that their GHPs have a solid niche in the industry, and EarthLinked is having wonderful success in the retrofit market. They have developed a few remarkable features on the EarthLinked Product lines.

The “EarthLinked Diagnostic Monitoring System,” version 1.0 now comes standard on all of their GHPs. It basically takes all of the guess work out of the diagnostics by showing the temperatures and pressures needed to trend diagnostics.  The feature comes with a micro SD card capable of storing decade’s worth of data.

Domestic Hot Water (DHW) generators are now standard features, complete with a DHW circulator and temperature controls.

The Smartphone app essentially places the refrigerant gauges, temperature sensors, amprobe and voltmeter, placing all of this information in the palm of your hand, without ever touching the GHP.  Isn’t technology great?

The smartphone places all of this information in the palm of your hand.

By the end of the year, EarthLinked says they’ll have packaged GHPs.  Currently, they match “off-the-shelf” air handling units (AHUs) with their GHPs.  Also, version 2.0 of their diagnostic monitoring system will have full complement of air-side information, including relative humidity (RH) and static pressure, which will enable remarkably accurate real-time monitoring and trending of energy efficiency ratings (EERs).

Those of us in the geothermal industry that have been slow to accept refrigerant based GHPs have a reason to take a 2^nd look; refrigerant based GHPs such as these certainly have an important place in our industry.

Jay Egg (l) and Joe Parsons.

Parsons Bio

By unanimous vote of its Directors at its meeting in Lakeland, Fla., the Geothermal Exchange Organization named Joe Parsons (Earthlinked Technologies) as its new GEO Chairman of the Board (2016-17). He has served on the GEO Board of Directors since May 2014. Parsons is Chief Operating Officer at EarthLinked Technologies, responsible for product development, training programs, standards compliance and authorized dealer relation-ships. He has worked for Earthlinked since 1996.

He enthusiastically accepted his position as GEO Chairman. During his career, Parsons served as President of Ray Company, Inc., an HVAC mechanical contracting firm. He was also VP of Marketing for Envirotherm Heating and Cooling Systems, Inc., an HVAC system manufacturer, and Director of Retail Operations for U.S. Power Climate Control, Inc. Parsons is a member of the International Ground Source Heat Pump Association Standards Committee, a member of the American Society of Heating, Refrigeration and Air-Conditioning Engineers and a Corresponding Member of TC 6.8 (Geothermal Heat Pump and Energy Recovery Applications).

He is also Project Committee Chairman for Standard 194, a voting member of the Canadian Standards Association Technical Committee (Ground Source Heat Pumps/ C448 Bi-national Standard Development), and Chairman of the Technical Subsection Committee C448.7 (DX). Parsons is a member of the Air-Conditioning, Refrigeration and Heating Institute (AHRI), and was elected Chairman of the Water Source and Geothermal Product Section at the AHRI Spring Meeting in March 2014.

He also chairs the DGX Product Subsection and DGX Engineering Committee, is an active member of the California Geothermal Heat Pump Association, and is a contributor to the Geothermal Heat Exchange Well Standards Update. In addition, Parsons works to advance geothermal technologies through participation in industry standards efforts in Australia.

Jay Egg is a geothermal consultant, writer, and the owner of EggGeothermal. He has co-authored two textbooks on geothermal HVAC systems published by McGraw-Hill Professional. He can be reached at jayegg.geo@gmail.com.

Particular care needs to be taken when piping a radiant system. This same care should be taken when securing wires on a PV system, but it often is not. One of my favorite things to check out on The Hub, is when John and Eric show these horrible examples of what not to do. I do not have any technical or hands on experience in designing, or assembling hydronics, just what I have learned from my buddy Bob “Hot Rod” Rohr at my time at Caleffi. But, I can obviously come to the reaction of, “What in the world was that guy thinking?!?”

Now I am in the solar industry, and I see a lot of similar practices. Some really good. And some really bad. Here are a few examples:

These are high voltage cables totally unprotected from the harsh environments that a PV system can face. Poor wire management can lead to long term system issues, similar to mineral buildups in pumps on radiant systems. Making sure you are protecting homeowner’s investments right away is critical, and it is often the small details that get over looked. These little details can add up to thousands of dollars in repairs in just a few years.

Through manufacturer-hosted webinars like we offer at HellermannTyton, called “Beyond the Panel,” we are able to discuss:

• Navigating you through shifting guidelines and regulations
• Teaching best practices critical to system performance, maintenance and cost of ownership
• Demonstrating why component materials and design matter
• Taking on other important industry challenges and changes in future webinars

Whether it is Coffee with Caleffi talking about hydronics, or Beyond the Panel talking about solar PV, these trainings are fantastic opportunities for free training that is invaluable when you are out on the job. What I enjoy most about these industry specific trainings, is we are creating a team of “lookouts”, spreading the word of sweating the small stuff. A lot of industry professionals already do this, but every person counts! By paying attention to the details, we can create a sustainable industry where the homeowner and business owners are happy with their investments for the life of the system.

Nick Korth is product marketing manager — Energies, HellermannTyton, Milwaukee, Wis.