Fellowship Hall Heating System

So for anyone who didn't know our 90 year old building is heated with steam.  Steam has the benefits of holding a large amount of heat.  The drawbacks of the steam system are: a very inefficient and wasteful system, slow heating; especially for radiators with no airflow across them, long initial heat up, very complicated system, difficult maintenance, and expensive repairs if a few crucial parts were to fail.  It has been the desire for quite a while to replace the steam system with something more modern.  This last summer we replace a large part of the steam system with a hydronic air handler heated from a donated small boiler.

The steam heating system was abandoned from the fellowship hall, nursery and side lobby area.  What previously required 11 cast iron radiators now involves about as many floor vents.  What used to take a good hour to heat now starts feeling warm in 15 minutes.

Background
In a common 2 pipe steam system water is heated to boiling temperature or a bit above and by its own pressure is distributed through steel pipes to each radiator in a system.  The steam heats the large chunk of metal and radiates heat to a room.  As the steam cools it becomes liquid again (called condensate) which a steam trap allows to flow past.  It then flows by gravity back to the boiler where it re-heated.

A hydronic heating system on the other hand heats water to a temperature below the boiling point of water and circulates water from the boiler to the air handler and back to the boiler.  The air handler has a radiator that works opposite to how a car radiator works.  The hot radiator has air blown through it which goes through ducts to the floor vents to heat the space.  The air in the room is then sucked back into the air handler and re-heated.  The vast majority of home and businesses used forced air heating as convective heat transfer is much more efficient and faster than radiative heat transfer.

Installation
The process of installing the new heating system involved a few main steps which were worked on through the entire summer of 2014.

1.  Install the new tankless water boiler:

- We were fortunate enough to get a small boiler donated to us over craigslist.  These typically cost a couple grand so this was very helpful for our bottom line.  They are similar to tank-less water heaters but instead of low flow and a high temperature gradient they use high flow low temperature gradient.
- The boiler was plumbed with a primary/secondary loop also heating the baptistery (through a water-water heat ex-changer), with two fittings for a future heating loop.

2.  Install air handler, ducting, vents, air intake, and return air handler:
- This was the most challenging physically as it meant crawling around under the fellowship hall to hang the air handler, route the ducting, install the registers, route and attach the water pipes.  Definitely involved some blood and sweat.

3. Removal of old system.
- Certainly the most rewarding.  After the system was up and running we could cut and cap off the steam and condensate lines, remove the radiators, and their boxes.  We kept the traps and valves and the metal radiators were taken by a metal recycler.

4.  Finishing touches
- Once the system was working in time for the winter heating season we could take a break and work on the various odd tasks like: painting the walls, repairing the carpet, painting the air return, roofing the air intake box.

A few months into 2015 the water pump on the air handler went out.  We were able to temporarily glue the impeller on until we replaced the pump.  We installed a new pump in the boiler room and left the old pump in the air handler (with the guts removed).

Benefits
So replacing this heating system cost us about $6,000 with an expected payback of 3 years.  The heating cost for the whole year should be about half the cost prior to the new system.  Since the Fellowship hall is used more than the sanctuary it allows the old steam system to be used much less frequently which both saves energy/cost and limits the need for maintenance on the steam system.  It also potentially gives the steam system hope to last a bit longer.

Future
While we would still like to get rid of the old steam system the payback on that would be much longer than 3 years.  With a cost of $10-20K and minimal cost savings this will need to wait a while.  The current plan is to convert the current steam boiler to hot water and re-plumb most of the building to work with hot water.