Dirty Work II

tim smith_2

I have worked on 100s, their longevity is incredible for cooling and heating via heat pumps. cooling towers sometimes can be an issue if chemicals not kept up. I am working on a bldg with 90 of the units right now. Have taken care of these for the last 12 years or so.

Ken_8

The dirty job is truly a unique one!

The "dirty demo work" thread portrays the "darker side" of stuff we all run into and is nothing new for those of us in the boiler biz. However, what the dirt was connected to and what the complete job entails is rather unique (at least for us). Here's are some of those details:

The W/M 94 we removed was oil, steam. The steam was sent to a nearby steam to water HX and thence to ~30 heat pumps. The heat pumps are water based and located inside and throughout the 4-story office building. In the heating months, the heat pumps require 70°F incoming water. From that water, the heat pumps harvest the BTU's and put out between 2 and 3 tons of heating output each.

In the summer, the steam boiler is turned off and the rooftop cooling tower does its magic.

We see evidence that the steam boiler was originally straight steam. We presume about 20 years ago, they removed the piping and radiation and switched to water-based heat pumps.

We determined to keep the heat pumps and simply eliminate the steam to water HX - and convert it to water to water. We kept the HX because the heat pumps - by virtue of the winter freeze exposure of the system water at the rooftop cooling tower - should remain anti-freezed. We don't like antifreeze in boilers. Because of the upscale nature of the tenants, those warm days in spring and fall might need cooling while those cooler days may require heat. Rather than preclude that desireably comforting ability of switching back and forth in the "iffy" outdoor temps, we wanted to be able to switch from Heat to A/C based on outdoor temps. In fact, we could have heat in the morning and cooling in the afternoon of the same day! By keeping the HX, we allow isolation of anti-freeze from boiler water.

The outrageous spike in energy costs easily justifies the use of condensing high efficiency boilers. The choice was between a modular battery of Weil McLain Ultra 310's - and an Aerco Benchmark.

We found the modular battery of 3 Ultra's a superior design for a bunch of reasons. The Tekmar 265 will be the system brain.

Get this. To maximize the 30 heat pump efficiency curves, incoming water temperature should be 70°. That means the Ultra output temps will be around 80-90°F! This allows a dT of 10-20° across the HX shell side (where the steam used to be - and now the Ultra boiler water will flow). Return water temps will be around 70°! We suspect the actual efficiency of the boilers will be as close to 99% as any application on the planet.

We are carefully photo documenting all phases of the job.

Anyone else here ever do a commercial office with water to water heat pumps and condensing boilers? Or are we "pioneers" on this one?

Ain't design/build nice!

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Wayco Wayne_2

Nice indeed

I have worked on a bank in the past that hada perimeter water source heat pump system that was supplied it's heate4d water from an array of 50 solar collectors and an electric boiler back up for dark days. It had a 10000 gallon storage tank in the basement. In the Winter on sunny days The heat pumps on the Solar side would run in cooling and the shady side would run in heating pretty much washing out the need for any heat from the solar system. That tank would store up enough heat to get through the night easy. However..... In the summer the only need for hot water was in the wash rooms for washing hands. The storage tank would soon overheat and pop off the pressure relief. I don't know how they came to terms with the problem as I left that company before they figured it out. This was early 80's and the panels are still up there. Wish I knew.

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Ken_8

Wayne?

What area/town was that system in?

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Wayco Wayne_2

Wheaton

Maryland. Equitable Bank on Georgia Avenue. 2 blocks from where I grew up. WW

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Mark Eatherton1

Bleeding edge technology...

You beat me to it Ken. I've wanted to do this for some time since I've been working with both the water source heat pumps AND condensing technology.

My only concern would be the HX sizing. If it was designed to deliver 70 deg water with steam temperatures (215 deg F), unless you've replaced it with a much larger surface area HXer, you probably won't be able to maintain 70 deg supply temps to the loop with an approach temp as low as 80 to 90 degrees F.

Another suggestion, for lop temperature control, use a "dead band" of 4 degrees F. In other words, if the return water temperature set point is 70 degrees, give it a 4 degree split differential between heat input vs. heat rejection. At 67 you start pumping in heat in, between 68 and 72, no heat is put in or taken out of the loop. It's merely exchanged by those core areas needing cooling, and those preimeter areas needing heat. When the loop hits 73 you start the cooling towers.

Good luck and keep us posted.

The tekmar 152 would do that for you real well.

ME

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Ken_8

Mark,

Thanks for the heads up. The Tekmar 152 would act in what capacity?

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Mark Eatherton1

Tekmar 152

auto switch over from heating to cooling modes with a good neutral dead band.

ME

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