Scary Chart Time: Oil Price Trends

By Luke Wonnell

For those of you who are considering an oil-to-gas conversion for your building’s boiler system, let’s take a look at the commodity price for a barrel of crude oil over the past 12 months – that’s right, it’s scary chart time!

Source: http://markets.businessinsider.com/commodities/oil-price?type=wti

The current $70+/barrel is 67% higher than mid 2017 when the commodity price was closer to $43/barrel.  Now, let’s see the trends over the past 3 years:

Source: http://markets.businessinsider.com/commodities/oil-price?type=wti

Although crude oil is still relatively cheap compared to the 2013-2014 prices which exceeded $100/barrel, the recent trends are definitely going in the wrong directions for the upcoming heating season.  Now, possibly for the first time ever, we’re going to show you the month-by-month equivalent price of a “barrel” of No. 2 heating oil (42 Gallons)… that’s just the type of service we like to provide for you here at The Metro Group.

Source: https://www.nyserda.ny.gov/Researchers-and-Policymakers/Energy-Prices/Home-Heating-Oil/Monthly-Average-Home-Heating-Oil-Prices

Since No. 2 and No. 4 heating oils are products of the crude oil refining process, the equivalent price per barrel is considerably higher than a barrel of crude oil (nearly double!).  Most buildings will benefit from keeping their fuel oil tank in place for backup or “interruptible” use, but it may be time to consider converting your boiler system to use Natural Gas as the primary fuel source in advance of the 2018-2019 heating season.

Call your Account Manager today to schedule a site assessment and see if you’re a good candidate for a gas conversion!

Sources:

http://markets.businessinsider.com/commodities/oil-price?type=wti

https://www.nyserda.ny.gov/Researchers-and-Policymakers/Energy-Prices/Home-Heating-Oil/Monthly-Average-Home-Heating-Oil-Prices

On Site Work: Replacing Manhole and Assembly

A manhole is an access hole typically located on the top side of the boiler.

It allows access for cleanings, washing out of debris and sediment, or repairs. The manhole should be opened annually, at a minimum, for internal inspection of the vessel.

When the cover to the manhole becomes corroded, it becomes both a safety and efficiency concern. If the manhole cover seals shut, the vessel cannot be properly inspected. If the cover seals incorrectly, with a space between the gasket and boiler, a steam leak can occur. This can happen on a steam boiler running for the purpose of creating heat. This will impact the boiler efficiency as you are losing steam while running the boiler for heat and also affect your fuel costs. While losing steam will cause you to burn more fuel, it is also an imminent safety concern as an individual who comes in contact with steam under pressure can be seriously injured. Any repair performed on a pressure vessel should be done by a professional, experienced, R-stamp certified mechanic.

ConEd Multifamily Gas Conversion Incentive Program – Must Apply Before May 18th!

By Luke Wonnell

ConEdison has structured a generous incentive program for multifamily buildings still on No. 4 heating oil, but you MUST submit your application BEFORE May 18th in order to qualify!  Click the link below for more information on this program:

https://www.coned.com/en/save-money/rebates-incentives-tax-credits/rebates-incentives-for-multifamily-customers/multifamily-gas-conversion-incentive-program-application

This program is structured for multifamily buildings with 5-100 units and prioritizes customers who are still burning No. 4 heating oil.  ConEd is offering a $500 per unit incentive (up to maximum $50,000) AND additional equipment incentives (up to maximum $25,000).  These incentives will help pay for a portion of the project and expedite your ROI on the gas conversion project.

In order to qualify for this program you need to act quickly.  Call your Account Manager today to schedule a site assessment and see if you’re a good candidate for this program!

Sources:

https://www.coned.com/en/save-money/rebates-incentives-tax-credits/rebates-incentives-for-multifamily-customers/multifamily-gas-conversion-incentive-program-application

 

See the source image

On Site Work

Highland Terrace – Westchester Co.

Below we have a new boiler installed with a dual fuel gas/oil burner.  This is a hydronic system.  We installed a Heat-Timer HWR control panel with a 3-way valve to provide precise heating water temp. control to the building.  The heating water temps can be fine tuned to react to outside temps providing very comfortable apt temperatures while significantly reducing fuel consumption.

Lindy Coils & Hot Water Systems: Part 2

When you’re in the heart of the heating season (October 1st through May 31st) and your boiler’s running anyway to heat the building, it’s an absolute no-brainer to use the Lindy coil and make all your hot water.  This is arguably the most practical and cost-effective way to produce all the hot water for your building during the heating season.

However, when you’re outside the heating season, the economics of running your boiler to make hot water through the Lindy coil become much less attractive and it may be worthwhile considering an alternate hot water heater solution.  For example, say you’re in the middle of summer with 150HP steam boiler (6,000,000 Btu/hr) firing up to provide a peak 40GPM hot water load (roughly 2,000,000 Btu/hr) in the mornings and evenings when everyone’s taking their showers or baths.  Because you’re outside the heating season, the boiler’s controls are essentially bypassed to an aquastat which measures the boiler water temperature.  This aquastat will turn the burner on and off several dozen times each day in order to maintain the boiler water above a certain temperature needed to provide instantaneous hot water.  So the burner kicks on to heat up several hundred gallons of boiler water, simply to heat a few dozen gallons of domestic hot water… not terribly efficient.

Imagine an alternate system setup where you install 1 or 2 high efficiency hot water heaters burning Natural Gas to produce your domestic hot water in the summer months.  Now that behemoth boiler can take a rest for a few months while the 90%+ efficient hot water heaters chug along and produce exactly the right amount of hot water for your building and turn off when hot water is no longer needed.

This configuration provides some much-needed breathing room for a PLANNED shutdown of your boiler.  Now you have the luxury of scheduling a few days in the summer to take your boiler offline for a much needed fireside cleaning, waterside cleaning, burner overhaul, etc. without ANY interruption to domestic hot water!

This setup will also provide critical redundancy of domestic hot water production.  If for some reason your boiler goes offline in the middle of January, you can now use the gas-fired water heaters to provide hot water to your residents instead of being completely out of both heat and hot water.

The Metro Group, Inc. is proud to offer full life-cycle support for all your boiler room needs.  Call your Account Manager today if you need to schedule a fireside or waterside cleaning, arrange for a burner overhaul, install a replacement Lindy coil, or if you’d like provide 100% domestic hot water uptime to your residents.

Sources:

http://www.dhtnet.com/products/dht-lindy-tankless-coils/

Lindy Coils & Hot Water Systems Part 1

By Luke Wonnell

If you own a Scotch Marine or cast iron sectional boiler in the NYC metro area, there’s an excellent chance you have one or more Lindy coils installed in the boiler, which provide all the domestic hot water for your entire building on an instantaneous basis.  Depending on the size of your boiler, there are Lindy coils available that can produce up to 10,000 gallons per hour of domestic hot water – that’s 167 gallons per minute – amazing!

Very simply, Lindy coils are bolt-on removable heat exchangers which allow the potable domestic water to pickup heat from the non-potable water/steam inside the boiler.  NYC boiler codes require the use of a mixing valve downstream of the Lindy coil, because the exiting water is well above scalding temperatures.  For Scotch Marine type boilers, the Lindy coil will typically be installed on the top of the front tubesheet (left photo below) while for cast iron sectional boilers, the Lindy coils are installed in one or more of the intermediate sections (right photo below).

There are many different configurations of Lindy coils available – the image below shows just a few of the available configurations:

Source: http://www.dhtnet.com/products/dht-lindy-tankless-coils/

Boiler Re-tubing: On Site Work

Below are pictures of a recent boiler tube replacement in Brooklyn. During this project we Torched and cut 25 old, corroded bottom boiler tubes (picture 1). Once cut, these tubes are removed from the boiler and the boiler room itself. The boiler vessel and tube drum are then flushed clean. Twenty five new U.S steel boiler tubes are then installed and rolled tight for a proper seal with the front and back tube sheets (picture 2). The boiler is filled with water, recharged with our inhibitor for proper chemical protection (a necessity with new steel and fresh make up water now inside the boiler), and the boiler doors are re-gasketed and checked for leaks. In addition to the replacing the boiler tubes, we also installed a new Dry Oven and interior insulating refractory wall (picture 3 and 4).

 

Heat Flux and Boiling Regimes: Part 3

In an ideal world, all the waterside metal surfaces inside your steam boiler would be exactly 86°F / 30°C above the boiling point when the burner is firing. This would result in perfect boiling everywhere throughout your boiler, maximizing the operating efficiency.  While this isn’t fully achievable in the real world, the manufacturer typically designs the boiler for Region I / II operation by providing at least 5 ft2 of heat transfer surface area per Boiler Horsepower. This ensures sufficient heat transfer surface area inside the boiler to avoid Region III / IV boiling.

By performing routine preventative maintenance (annual fireside cleaning, periodic waterside cleaning, and annual burner overhaul/tune-up) you will keep your steam boiler operating in tip-top shape and avoid Region III / IV boiling. Call your Account Manager at the Metro Group today to learn more about our preventative maintenance services!

Sources:

http://www.thermalfluidscentral.org/encyclopedia/index.php/Pool_Boiling_Regimes

https://www.youtube.com/watch?v=N1yZwRcQSZw

Heat Flux and Boiling Regimes: Part 2

What’s really interesting is that if you were to crank up the burner to 11 at Step 5 and allow the surface temperature of the bottom of the pot to continue increasing, the heat flux through the bottom of the pan absolutely falls off the cliff.  That’s peculiar… despite the fact we’ve added more heat, the heat transfer has dropped – how could this be?

In this scenario, the water at the bottom of the pot enters the dreaded Region III (Transition Boiling in ORANGE) or even worse the insidious Region IV (Film Boiling in RED).  In these boiling regimes, large vapor bubbles form sporadically and cling to the bottom of the pot, acting as an insulating barrier.  This “film” of vapor makes it MUCH more difficult for the pot to transfer heat from the burner to the water.

You desperately want to avoid Region III or Region IV boiling inside your steam boiler at all costs.  The unpredictable formation of this vapor “film” causes localized hot spots on the metal surfaces which will cause surface cracks and lead to premature failure.  Region III/IV boiling will occur when years of corrosion/erosion of the tubes thins out the material to a point where the local surface temperature overheats.  It will also occur if a burner is not tuned properly and is overfiring for the rated capacity of the appliance (e.g. a burner is firing at 100HP for a 90HP boiler).  Finally, fouled fireside or waterside conditions can also contribute to this scenario.  If you notice unusually high flue gas temperatures, there’s a good chance parts of your boiler are operating in Region III and/or IV.

Heat Flux and the Boiling Regimes: Part 1

By Luke Wonnell

Besides being a wicked awesome band name, the title of this article refers to some 201 level Thermodynamic principles that have a significant impact on the performance of your steam boiler. “Heat flux” defines how much heat transfer occurs through a given material’s surface area and is expressed in (Btu/hr-in2 or W/m2).  Think of the bottom of a pot as the given surface area… the heat flux simply defines how many Btu’s/hr will be transferred through the bottom surface of the pot.

What’s amazing about heat flux is it’s not inherent to a specific material… it’s not like Cast Iron has one particular heat flux value and Carbon Steel has another different heat flux value. In fact, the heat flux value (vertical y-axis) changes in very interesting ways as the surface temperature of the metal that’s in contact with the water increases (left to right on the horizontal x-axis) as shown in the diagram below:

Source: http://www.thermalfluidscentral.org/encyclopedia/index.php/Pool_Boiling_Regimes

Let’s walk through this diagram by using a real-world example of boiling a pot of water on the stove for Thursday night spaghetti dinner with the family:

Step 1 – After turning on the burner, the tap water (starting at approximately 60⁰F) in the pot slowly increases in temperature until it hits the boiling point (212⁰F). By the way… don’t watch this part, otherwise Steps 2 through 5 will never happen.

Step 2 – Once the boiling point is reached (212⁰F), the water at the bottom of the pot enters Region I (Natural Convection Boiling in YELLOW) but there are no bubbles forming yet.  The warm water towards the bottom of the pot circulates towards the top and the cooler water falls to the bottom.

Step 3 – Once the surface temperature of the bottom of the pot reaches 253⁰F [41⁰F / 5⁰C above the boiling temperature], the water enters Region II (Nucleate Boiling in GREEN) and you will see tiny bubbles forming on the bottom of the pot and rising to the surface.

Step 4 – As the surface temperature of the bottom of the pot continues to increase, you will see (and hear) more bubbles and larger bubbles rising to the surface.

Step 5 – Once the surface temperature of the bottom of the pot reaches 298⁰F [86⁰F / 30⁰C above the boiling temperature], you have reached perfect boiling where you are most efficiently conducting thermal energy through the bottom of the pot.  Engineers like to call this the critical heat flux, but I prefer “maximum boilage”.  This is typically when you throw in the pasta and turn off the burner.

For an excellent video demonstration of the different boiling regimes, visit:

https://www.youtube.com/watch?v=N1yZwRcQSZw