Tour the Mechanical Room

Have you taken a virtual tour of our new energy-efficient Mechanical Room at the Taco Innovation & Development Center (IDC)?

We invite you to visit Center’s dedicated mechanical room, a showcase for the latest in energy savings and sustainable products and systems available in the HVAC industry today. The building includes advanced hydronics system applications such as radiant cooling, radiant heating, snowmelt, geothermal and solar thermal in a total of 25 “Living Laboratories” that provide for hands-on learning.

In this video, Rich Medairos, project mechanical engineer, walks you through the highlights of this sophisticated, integrated installation incorporating a variety of design strategies for an energy efficient building including:

• Active chilled beams.
• An energy recovery unit.
• Solar hot water generation.
• The iWorx system building management.
• High-efficiency pumps, chillers and boilers.
• Variable speed pumping applications.

Take a virtual tour now: http://bit.ly/O5e4Ev

Pumps Don’t Head: Valves Do (Part Two)

Comparing Total System Horsepower: VAV vs. Chilled Beam-LOFlo Systems 

By Greg Cunniff, Applications Engineering Manager, Taco, Inc.

This is the second part of our discussion series “Pumps Don’t Head: Valves Do”. In the first part, we examined how we calculate pump energy consumption.

Now lets graphically compare total system horsepower or electrical demand in the case of energy efficiency for an all-air VAV system, a conventional chilled beam system, and Taco’s LOFlo chilled beam system.

A comparison of peak power demand for a low-flow injection-pumping system.

A comparison of peak power demand for a low-flow injection-pumping system.

It’s interesting, and we’ll be the first to admit it, that the efficiency of a LoadMatch circulator used in the calculation is quite low. But focusing on the efficiency of the LoadMatch circulators misses the point, because the lower efficiency LoadMatch circulator does not see much head, so a LoadMatch system (or a LOFlo system which employs LoadMatch circulators) still has a lower overall pump horsepower.

The point is that pumps, regardless of how many are used, do not impose head on a system. Control and balancing valves do. Therefore hydronic systems like LoadMatch and LOFlo – using pumps instead of valves – will have lower overall pump horsepower.

Then there’s the use of variable speed drives to further reduce pump horsepower and energy consumption.  In a single pipe system, like LoadMatch, the VFDs are controlled from Delta T (differential temperature) and not Delta P (differential pressure). Pump mounted VFDs with an integral controller, which Taco now offers,  can sequence both Delta T and Delta P. In fact, Taco is the only pump manufacturer presently offering both control sequences in one on-board controller.

In conclusion, adding pumps doesn’t add head – they work to eliminate head. Single pipe systems (like LoadMatch-LOFlo) achieve savings in pump horsepower by splitting the horsepower between the primnary and terminal secondary pumps. Using a single pipe system eliminates the need for all control and most balancing valves, which in a conventional two-pipe system add head.

The takeaway: hydronic systems are more efficient than air systems and single pipe hydronic systems are the most efficient of all. We are interested in learning about your opinions and experiences.

Pumps Don’t Add Head: Valves Do (Part One)

Pumps Don’t Add Head: Valves Do (Part One) 

Greg CunniffBy Greg Cunniff, Applications Engineering Manager, Taco, Inc.

Net-zero green buildings are in vogue today and for a very good reason: they are meant to operate at no net energy consumption, drawing no net energy from the electrical grid. This sustainable capability is accomplished through a combination of energy efficiency and on-site energy generation, often through co-generation.

A reader recently asked us if there is data to support a claim that electrical consumption in a system employing Taco’s LOFlo injection mixing system would be less than a traditional design with control valves.  To be more precise, what he is getting at is if there would be less energy used in a system configuration using single pipe with two sets of pumps in a primary-secondary configuration vs. a system using one larger pump set along with control valves in the building’s zones.

To answer the question, we need to examine how we calculate pump energy consumption, which is a simple first law problem. And we should take into account today’s variable speed drives which are specifically designed to reduce energy consumption.

First off, it doesn’t make any difference how the pump horsepower is split up. What counts is the total flow and the total head in a system – e.g., placing 40% of the pump head on one set of pumps and 60% with the other.   The total pump horsepower will be the same if the efficiencies of the pumps are the same.

In Taco’s case, using our single pipe LoadMatch® and LOFlo® systems, we can achieve savings in pump horsepower by splitting the pump horsepower between primary and terminal secondary pumps.  This allows for a pump controlled system without control valves and a self balancing system without balance valves. This will save between 15 and 20 ft. of pump head on the total system, depending on how the valves are sized.

For our LOFlo injection mixing system, a three pump system with primary, secondary injection and secondary terminal unit pumps, it doesn’t make any difference if we have two secondary pumps instead of one. Adding pumps does not add head – it eliminates head.

Here is an example of how one can calculate the head in a system with and without using LOFlo.

To calculate pump horsepower multiply head x flow x a conversion factor, divided by the pump efficiency in both loops/ The calculation of total pump horsepower would therefore be as follows:

Conventional system:

Horsepower = 200 gpm x 68 ft./3960/.70 (pump efficiency)

= 4.9 hp

LOFlo system:

Horsepower = 200 gpm x 46 ft. (head of primary and secondary house loop)/3960/.70 (primary pump efficiency) + 200 gpm x 5 ft. (head of terminal unit loop)/ 3960/.25 (efficiency of LoadMatch circulators)

= 3.2 + 1.0

= 4.2 hp

This represents a savings in pump horsepower of 14%, which is not trivial.  In the real world achieving net zero is actually impractical from a cost standpoint as well as impossible from a first law standpoint. However, we can use it to our advantage since it is our firm contention that hydronic systems are more efficient than air systems.

Next up: Comparing Total System Horsepower: VAV vs. Chilled Beam-LOFlo Systems

Safety Concerns with VRV-VRF Systems

Water vs. Air: Safety Concerns with VRV-VRF Systems

Greg Cunniff, Applications Engineering Manager at Taco, Inc.

Greg Cunniff

By Greg Cunniff, Applications Engineering Manager, Taco, Inc.

In our continuing discussion of water vs. air systems, particularly with regard to hydronic chilled water systems vs. DX-type air systems like VRV-VRF, the issue of safety arises as a concern. That’s due to the presence of toxic refrigerant used in VRV-VRF systems. Your author relates a personal experience below, one that I was fortunate enough to have survived to tell about…

The major concern about VRV-VRF systems is the safety factor stemming from a refrigerant leak. As refrigerant is a toxic fluid, applicable codes (ANSI/ASHRAE Standard 1502001 and the IMC) restrict the amount that can be used in a single refrigerant circuit. Refrigerant is classified as a hazard to human health and the codes place restrictions on how much can be discharged into a living or work space. Refrigerant fluid is heavier than air and because of that it displaces oxygen in a room – if it takes enough oxygen out of a space a person exposed to it can suffocate. Because refrigerant can’t be readily detected by human senses – it cannot be seen or smelled – codes require refrigerant alarms in spaces where the concentration of the fluid is enough to cause a lethal accident.  Years ago that was not the case.

This author, in an earlier career phase, had a potentially lethal encounter with leaking refrigerant. As a manufacturer’s rep agent back in the 1980s I had supplied a large DX system to a school. One day I was called out to the school because there was a problem with the system’s refrigerant distribution. I was joined by a factory representative who discovered that a check valve had been installed backwards in the refrigerant receiver.

Being younger men we decided we could fix the unit on the spot – unscrew it, screw it back in correctly and walk out of there, job done. So the tech unscrewed the valve from the piping. Being a fairly large receiver there were many pounds of refrigerant under pressure. With the pressure so high and the velocity of refrigerant coming out being so great, the tech found he could not get the valve screwed back in. The fluid was literally streaming out into what was a rather small mechanical room. In less than a couple of minutes the escaped refrigerant had built up in that room to make both of us pass out.

What saved us was an alarm going off which woke me up. I was still standing but the tech was on the floor.  I literally dragged him out of the room and got the door shut. The alarm that saved us was not a refrigerant alarm but rather a fire alarm – positioned outside the mechanical room – which thankfully could detect gases as well as smoke.

Next Up: Liability Concerns for the Engineer

Water vs. Air: Variable Speed Technology

Water vs. Air: Variable Speed Technology

Posted by Greg Cunniff, Applications Engineering Manager, Taco, Inc.

Variable speed hydronic circulation has been around for years, and with the advent of packaged controls on pumps, it’s easier than ever to implement.  Variable speed pumping operates on this simple principle: it is based on heating or cooling load demand.

The objective is to satisfy the heat gain of a structure as efficiently as possible. The way to do that is to allow a pump to adjust its speed to deliver the required heat. By maintaining a consistent delta-T, flow can be varied as needed to ensure optimal performance and heat transfer.

Chilled water systems have employed variable speed fans with variable air volume (VAV) systems for more than a quarter of a century as well as variable speed pumps.  DX-type systems have essentially functioned as constant volume systems using one evaporator coupled up with an air-cooled condenser along with a set of refrigerant pipes in between.

DX manufacturers have finally incorporated variable speed technology within their systems, using multiple evaporators on a single condensing unit, essentially making a chilled water refrigerant system. To make the system work, a variable volume of refrigerant is needed for each evaporator. So the good news for DX systems is that their level of efficiency has increased, just as it has increased for all-air systems, VAV and variable volume chilled water systems.

With today’s refrigerants, like R410, compliant with the Montreal Protocol’s direction for less environmental impact, they are not as efficient as previous CFC refrigerants in generating the amount of BTUs needed for today’s systems. Today with rising energy costs and the use of less efficient refrigerants there’s a need for variable speed technology to provide higher efficiencies.

What’s your opinion of variable speed technology and its energy efficiency impact? Are you employing VFD-equipped pumps and compressors?

Next up: The safety issue with VRV/VRF systems.


Hydronics Vs. Air: Radiant Cooling

By Greg Cunniff, Applications Engineering Manager, Taco, Inc.

In comparing hydronic chilled water and VRV/VRF systems, a new emerging factor for the chilled water side of the equation is radiant cooling. Radiant cooling is an exciting feature that avoids some of the challenges with space cooling distribution common to both types of air conditioning systems.

Comfort cooling is dependent on cooling coils and fans in the form of fan coil units or heat pumps along with filters (in the case of critical areas high efficiency filters). In lower end systems lower performance grills and air diffusers are commonly used, which can aggravate the comfort problem by dumping cold air on occupants. A radiant cooling system, however, avoids these problems since chilled air is not distributed through an air distribution system, as described above, but rather by a combination of radiant and natural convection. This only serves to improve IAQ.

Radiant cooling systems are now coming of notice here in the U.S. and design engineers are turning to them to achieve high comfort levels. Radiant cooling, like most hydronic-based applications, is common in Europe, but the trend line here in the U.S. is encouraging. There are a number of domestic radiant cooling manufacturers around today with successful installations.

At Taco’s Milton, Canada operation we have installed a chilled beam system to cool the office and training areas during the summer months.

Chilled Beam installation at our Taco’s operation facility in Milton, Canada

In this application active chilled beams were employed along with chilled ceilings to supplement. Together they work to reduce fan energy by a factor of 10, since the only air circulation that’s required is from the DOAS. This system supplies just enough treated, dehumidified outdoor air to slightly pressurize the building, negating natural infiltration of humid outside air. Like its counterpart, radiant heating, the market for radiant cooling will only grow larger in the years ahead, now that use of 100-percent DOAS is understood to be an effective remedy for the dehumidification issue previously associated with radiant cooling.

Hydronics = Fluid Comfort

Hydronics = Fluid Comfort

Water Vs AirSteve Clark, P.E. has written a perceptive and provocative article (Hydronics vs. air…and the Clear Winner ) on the greenbuildingpro website, which argues that hydronics (which he defines as fluid comfort) should be the preferred means of heating and cooling in U.S HVAC systems – far beyond the paltry six percent he cites for new commercial projects – if U.S. engineers would embrace the energy-efficient space comfort systems of their European counterparts.  Americans’ notion of temperature control is, unfortunately, as he points out, a bit antiquated – we are accustomed to employing energy-wasting systems like forced air, electric heat, through-the-wall A/C and split systems to cool interior spaces rather than using energy saving radiant cooling, as an example, as the Europeans do.  As he points out, “When a client asks us to engineer a comfortable space, we give him a forced-air A/C system.”

FC hydronic systems will sooner and more efficiently get us to the goal of Net Zero.

What is your approach to comfort issues?

Water Vs. Air: Dehumidification Issues

Water Vs. Air: Dehumidification Issues

By Greg Cunniff, Applications Engineering Manager, Taco, Inc.

Another major issue between water vs. all-air systems is how chilled water and DX-type systems treat     humidity, a critical consideration in providing air conditioned comfort. Humid climates in particular   provide a mismatch between the sensible heat ratio and the load in DX systems. In order to adequately remove moisture from a space or zone, cooling coils need to remain online for as long as possible in order to adequately remove all the moisture. However, the sensible heat ratio of the load is generally lower than the sensible heat ratio of the coil. If the coil is cycled based on sensible heat or outside air temperature, then the moisture remains, to be re-evaporated back into the space. Water also is left sitting in the drain pan.

Chilled water systems will provide much better dehumidification due to the fact that coils can be selected to provide a sensible heat ratio of the load. Plus, reheat systems can also be incorporated in extremely humid climates. Chilled water systems can even reheat at the zoned level, if desired. Taken together, buildings cooled with chilled water systems will have higher comfort levels than typical DX systems.

Have you designed A/C systems for use in humid climates using either hydronic or air systems and, if so, how have they fared in operation with regard to controlling humidity. Join the discussion.

Next time: the emerging world of radiant cooling.

Comparing Water vs. Air

Comparing Water vs. Air Water Vs. Air

In the HVAC world there are two principal delivery systems employed to provide indoor air comfort – water (hydronics) and air (direct expansion systems or DX for short) – and each has its proponents and schools of thought. But is one delivery system better than the other and, if so, how and why? Is one better than the other in terms of costs, comfort levels, indoor air quality, energy use, and even safety? That’s the discussion we want to develop via this blog, and we’d like you to weigh in. Naturally, we think that a hydronic system is a better offering than an air system, especially for air conditioning, and we’ll be offering a number of reasons in support of that view.

Traditional hydronic chilled water systems have long provided very comfortable and reliable air conditioning, and they come with several major advantages: excellent indoor comfort (especially with multiple zones), lower energy costs, and improved IAQ. Plus, there are new developments occurring with hydronic-based chilled water systems: the growing popularity and use of radiant heat systems that now include a radiant cooling and chilled beam options, and the emergence of a new single pipe system that can dramatically lower the usually higher first costs of a hydronic system in comparison to a DX system.

DX systems have been around for a long time but larger commercial DX systems – VRV (variable refrigerant volume) or VRF (variable refrigerant flow) – are now on the market.. VRV has been called “another refinement of DX refrigerant split systems.” Unlike earlier versions of refrigerant split systems that employed multiple condensers, evaporators and refrigerant lines, VRV/VRF systems use only one large outdoor condenser and one set of refrigerant pipes for the entire building, with a separate evaporator for each building zone, similar to a hydronic chilled water system.

In essence, VRV/VRF systems are made up of a central chilled water system with refrigerant pipe. In doing so, the cost of a DX system has come down in price. That’s important because chilled water systems are typically more expensive to install than DX systems, resulting in higher first costs. However, to select a VRV DX system over a chilled water system based on first costs alone would be shortsighted, considering our contention that chilled water systems provide more benefits overall.  More important chilled water systems are safer since occupants are not exposed to an unsafe concentration of refrigerant if a leak occurs

In citing those benefits, none is as valuable as the end result: optimal indoor air comfort, regardless of a building’s size, configuration or climate setting. Hydronic systems provide superior comfort to all other available options for comfort air conditioning – VRV systems included.

With a chilled water system it’s easier and less costly to provide multiple zones of temperature control, particularly in larger buildings, because multiple terminal units (fan coils or heat pumps) are linked to one set of central generation equipment. One of the traditional concerns with chilled water systems has been balancing the system upon start-up and commissioning. However, the development of automatic flow control valves that can automatically adjust for differences in pressure and flow rates has improved balancing of hydronic systems. And with the advent of single pipe systems that self-balance, system start-up and commissioning has become that much simpler.

Next time: more on the innovative single pipe system and its benefits. In the meantime, let us know your system delivery preference and why.

Posted by Greg Cunniff, Applications Engineering Manager, Taco, Inc.

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