CInema Theatre Heating

DavidMitten

Hi
I just took a look at the heating and cooling system for the local cinema theatre in town. I surveyed it because the system has a steam boiler and they would like to replace it.
Although the system utilizes a steam boiler, it does not use radiators. Instead, it is set up as a massive air handler with the steamer running through a heat exchanger in the adjacent room.
This room also has evaporative cooling in front of the heat exchanger, but that might be a different story.
I have a background in water process systems for auto plants, and the air handler part was much like what you see redundantly in paint shops with downdraft booths, or humidification systems.
Is this a common setup for a theatre or commercial buildings?
I am looking for an installer to do the job. I already opened my big mouth and said: " keep the steam".
This is in the city of Traverse City, Michigan.
All the local contractors who have looked at the system want to tear it out and put in hydronic systems. I am assuming this is due to ignorance, but I could be wrong. That would it seems entail resizing and replacement of the exxhanger though.
They also want an autonomous ice melt system installed in the same room. It would melt the sidewalks in front of the theatre and maybe two hundred feet of city sidewalk. So, that is part of the equation too.
Thanks for your input.
David

Jamie Hall

No reason not to keep the steam. As you note, the steam runs through the air handler and heats that air through the heat exchanger. You would need a much larger heat exchanger if you went with hydronic!

Also note, however: the steam pressure may be significantly higher than that found on a residential system, and the air handler heat exchanger, controllers, and traps sized and spec'd accordingly.

It is possible that the evaporative cooling does much in the summer time, although it might -- depends on relative humidity -- but what it may be doing, at least in part, is controlling humidity all year round -- using the heat exchanger to raise the air temperature above the desired set point, then using the evap. cooling to humidify the air and bring the temperature down to set point.

Is this common? Haven't surveyed a whole lot of theatres, but the one in a nearby city which was recently restored uses almost exactly the same setup.

You might be able to use hydronic off the steam boiler for the snow melt; that would depend on the boiler size and the actual snow melt load.

A further thought: part of the job not to be neglected is going to be to thoroughly clean all of the ducting and plenums.

DavidMitten

Thanks Jamie.
Yes. I think it would be easiest, and cheapest if they simply replaced the boiler. I don't think it is a high pressure Boiler. It was firing while I was there with 0 on the guage. I will look it up though.

Yes. One of my concerns with switching to hot water system is that they would need a larger exchanger, so that would need to be included in the job.

With the snow melt, they want it to be completely separate. In accounting terms, this makes sense, because other building owners will be contributing to fuel and maintenance costs for the ice melt boiler.
I suppose that one boiler could do the job of heating the building and melting the ice, then the other store owners could simply contribute to a percentage of maintenance cost of the boiler. My intuition says that it is probably cheaper to install a separate boiler for the ice melt function though.

Pumpguy

I too have seen similar theater heating systems to what you describe.

My only involvement was with the vacuum condensate return pumping equipment; upgrading and overhauling to meet current loads. This included piping changes to comply with current recommended practice.

Depending on what's there now, and how the system is operated, including operating steam pressure, it might be worthwhile to look into the advantages available with a vacuum return system. You could easily heat with 2 PSI steam pressure, and probably even less.

That said, other uses for the steam, like snow melt or humidification might require a different operating steam pressure.

Send me a PM if you would like to discuss details.

EBEBRATT-Ed

The only theater(s) I was involved with the equipment was horribly undersized. I finally decided that it would only maintain the buildings at "set back temperatures" when unoccupied.

When occupied the theater goers heated the building.
So if the movie sucks your going to be cold watching it.

A good movie makes a warm theater!!!

Zman

For the snowmelt think condensing boilers. They love the low return temps. Usually easier to vent in a retrofit as well.

WayneMech

I have to agree with Jamie, et al, that steam is the way to go. Agree with Zman, as well. Mod/Con snow melt is wonderful. It is also a much easier financial disconnect from the Cinema heat system, which strengthens trust between those paying for the snow melt.

wcs5050

Run mod/con into a well-sized buffer tank to serve snow melt dedicated, and boiler will run low and slow at great economy.