Mausoleum heat retro ???

Brad White

1) System distribution is in place (ductwork, grilles, etc.) so first cost basis is preserved. No collateral opening of walls, tombs and hard marble surfaces (I assume) to run new piping or other distribution.

2) Water temperatures can be modulated for much greater efficiency than an on-off one-temperature furnace.


Overall much more efficient use of fuel and existing infrastructure.

The comfort will assure a Grateful Dead who will thank Tim upon resurrection.

:)

tim smith

Mausoleum retrofit questions

Hey all, have a large mausoleum, 50ksft. Has old scorched air counterflow furnaces, gas converted. Blowers still in ok condition but heat x cracked on both. Thinking of putting large water coils in plenum and installing either 3 to 4 prestige 399 mod/cons or 1 Aerco benchmark or????? Any ideas would be appreciated. Load is appx 1.2 million btus. I have sized water coils but still unsure on boilers. Also thought about 1 larger cast iron sectional w/ power burner. Think mods would be better even though high temp water needed at design. Tim

Brad White

This takes \"perpetual maintenence\"

to a new level...

If the air distribution ductwork is sound and well-sealed, I see no reason not to take a hydro-air approach. I would take the time to measure the current airflow and assess the fan-side of things. Overhaul bearings, new belts and sheaves, etc. In the end, new blower-coil units may pay dividends and can make a nice, cleaner alternate. No fussing with older equipment which will only give you repaired older equipment...

You could very well work this system entirely within Mod-Con condensing range IF the airflow rate is high enough to deliver those BTU's.

Do you have a handle on what the airflow rate is? A few hours from a TAB tech to take airflow measurements would be well-spent. If it gets you to keep the air-side distribution and maintain condensing temperatures for more hours of the year, that has a demonstrable payback.

My guess is that the entire space uses nearly 20-25,000 CFM of air, over how many furnaces I do not know. But the point is, if your airflow is high enough (more air at a lower temperature) and the ductwork can support that, you can certainly get coils with more rows, 4 or 6-row coils, which can work well with lower water temperatures.

For boilers, the Hydrotherm KN has a 600 MBH model, 1MM and 2MM models. Maybe a combination of a 1MM and a 600 MBH might work for you, allowing the 600 to do most of the work for much of the year and the 1MM to take over when cold at which point the 600 can fill in. These boilers can boost to "normal" or conventional 180F water as needed so you are covered if you cannot get low-temperature coils.

The other boilers seem fine but the Aerco starts at 2MM input so would be over-sized. Besides, I like redundancy in applications such as hospitals, prisons and now mausoleums, where you cannot send the people home....

The good news is, if you fall short, the occupants will not complain much.

tim smith

Air flows etc

Brad, I do have a handle on the airflows and one of the two blowers has been rebuilt with the other one in fair condition. Air flow at appx. 8000 cfm each. One note, we are thinking of undersizing some to maintain 60 at outside design of 24 as it is less than probably 10 days a year we are sub 30. Which when this happens here no one goes out to a mausoleum. I have tetatively sized water coils w/ waffle fin design. Further input appreciated. Thanks, Tim

Brad White

Air Flows

At 16,000 CFM available versus 1.2 MMBH, you will have or need a 69 degree temperature rise, so 129 degree air when it is 60F in the space.

I see a high temperature coil regardless, using at best maybe 150F entering water and 130F leaving. Maybe that is optimistic. More rows is not a bad thing but imposes a pressure drop that the furnace never did. Of course you know this.

Still, I think your approach is sound.

jp_2

why?

why would you convert to hydro air?

a FA furnace heats the heat exchanger directly, now you have to heat water to heat the air heat exchanger???