Commercial Boiler replacement

@gpjazz

I would say no as long as each boiler does not exceed 250,000 btu. But that is just my opinion. Since it is a commercial job the inspectors may want it.

The states adopt the CSD-1 but some states modify it so you will have to check.

If you install high efficiency boilers seriously consider installing a dirt mag. There is probably rust and mud in the system piping. NOT good for new style boilers. May even want to flush out system and add inhibiter.

Lots of good advice on fitting removal from HH pros in the thread below. Watch @Gordo 's video cutting a slot into the fitting and wedging the slot open to relieve pressure on the threads, then unscrewing.

@gpjazz Yes, normally those would still apply. At least in Illinois my inspector would mark the entire system as "one boiler".

@gpjazz I suppose if the inspector insists you would have to put a solenoid valve in the water heater supply pipe. I guess it would have to be a NC valve and the power is shut off with the emergency switch. The other option (which he may not like) is a NO valve that would be closed in an emergency that would prevent having a valve energized 24/7.

Depends on the size of the boiler and the state code. In MA. if the boilers are over 250K input each we have to have and LWCO and a manual reset LWCO on each boiler for steam and an operating pressure control and a man reset pressure control on steam. for each boiler.

Hot water would require a 1 man reset LWCO on each boiler and a man reset aqua stat on each boiler along with an operating aqua stat (non manual reset) on each boiler

Thease are not arbitary. You need to find the state code in your area and read what they want. it exists somewhere.

Contact: Call 717-214-4319

PA Dept of Labor and Industry

Boiler Division

651 Boas Street, Room 1606

Harrisburg, PA 17121

These are all questions you should be asking the inspector directly.

I would have the system filled and ready to run. I have never heard of a "rough inspection" and a "finish inspection" for heating except for gas piping maybe.

But all states and inspectors are different I guess.

In your case (these are replacements correct) the existing system is presumed to be ok. You just need to get the controls and boiler piping correct.

Is it possible for you to install "King valves" on the supply and the return mains? Obviously depends on the piping but I try to do that on all of the water boiler systems so that I can isolate the boilers and remove them and put them back in without draining if possible.

I can't imagine a piping change that they would require that would need you to shut down the entire building except one. I believe that just recently in Illinois there's been a change so that if you have a multiple boiler system each boiler there has to have two low water cutoffs and you can no longer have a shared one. You used to be able to have each boiler with one standard low water cut off and there could be a Central manual reset one above all of them. But that's no longer allowed and they each need their own individual secondary low water cut off so a total of six I think in your case. But that depends on the rules. And there can't be any valves between the boiler and those low water cut offs.

Are you eliminating the 2 steel compression tanks hung in the ceiling or eliminating them?

Based on your drawing and my experience with hydraulics repair and maintenance you will have trouble maintaining the flow of hot water because of the weight of the water above it because of the laws of fluid dynamics.

Has the system been so badly butchered that a gravity system would not work? I would contact Bell and Gossett and ask for help with this as a bottom fed gravity hot water system leaving the basement steel compression tanks alone as is would still work if there is no room for a tank on the top floor fed by a circulator with a single riser to act as a nurse tank.

If the old boiler is not leaking it would make more sense to install a second boiler of the same size in series with the old one and a third steel compression tank in series parallel and have bypass piping and valves of the same size as the main piping installed at the same time that would allow for bypassing the old boiler in a worst case scenario in my opinion.

The Dual fuel boiler information and product material I forwarded to you with its correct pipe size would do this and you would only open the loading door on the boiler to brush out the boiler walls and remove the gas burner from the secondary fire chamber to clean out the fire box for the single gas burner when needed. You would be able to leave the current steel compression tanks in place as well. You would need three additional barometric dampers; one for each boiler as designed.

If you install a bladder expansion tank you would not be able to use the steel compression tanks at the same time as the steel compression tanks are the management system where a an expansion tank system is an air elimination system.

As Mr. Holohan is so fond of saying "be the ball" and you will see where the water is going down the pipe. having smaller piping entering the larger piping in the basement will increase the resistance to water flow simply because of the water weight above the boiler(s).

It would help a great deal if we had more pictures of the radiators and the piping in general.

The other worry is the chimney and its condition and whether you can install three separate flues to breech the chimney.

You can never outrun the laws of fluid dynamics and physics unless you have a properly designed bottom fed or top fed system. I believe you will need to make the hot water much hotter to simply get it to rise faster in the water column to the top floor.

Finding out if the radiators have restrictor discs in them would be the first thing to check on the list. If the radiator piping has not been butchered and this was a gravity fed system at one time you can use the existing piping to your advantage.

How is the domestic hot water handled in this system? Does is use separate gas fired water heaters or a common hot water system using a circulator feeding all the hot water lines in the building?

Make sure you use an air separator that has a pipe connection to route the air back into the tank. This will keep it from waterlogging. Also install an Airtrol fitting on the tank.

Again, I am not an expert, so take an expert's advice if they can show I'm wrong. But AFAIK, the Tekmar 294 can only tell which boilers to run based on ODR target temp of the supply. You say there's a return sensor, but I don't see one on the Tekmar 294 wiring diagram. And even if all three boilers are running simultaneously from a cold start, depending on how much water volume there is in the system, it could take 30+ minutes for all three boilers to raise the return water above 130. Meanwhile you spent 30 minutes condensing. Then in mild weather when ODR is targeting, say, a system water temp of 120, what do you think the average return water temp is going to be? It's going to be under 120 all day long, for most of the heating season.

I manage a 4-unit 100-year-old building in Boston with all cast iron rads and two cast iron boilers about the size you're installing, and I can guarantee with all your cast iron rads, your ODR water temperature is going to be 130 degrees or less for most of the heating season. So how is the Tekmar going to make the return water hotter than 130, when the supply water temp itself is only 130 or less? The only way to do that is to program the reset curve to give you, say, 150 degree water all year so your return never drops below 130…which kind of defeats the whole point of ODR.

The way to take maximum advantage of ODR is to run as low a supply water temp as possible, which is going to be below condensing temp most of the season in your situation. So as far as I can see, you will absolutely need return water temp protection on each boiler. And the savings from ODR is going to far outweigh the cost of adding three bypasses.

If you build a pump module for each boiler you can be sure to remove all the air out of the system by using an Internal Air Separator for each boiler placing it at least 12 inches before the circulator.

Mr. Holohan has well drawn pump module drawings in his well written book "PUMPING AWAY" that you could use to create the pump modules to pump away from the boiler and quickly remove the air bubbles in the system.

Using Isolation valves for each circulator in a pump module will allow you to change a circulator if needed without out draining the boiler. Using Isolation valves with gauge ports will let you keep track of the vacuum created by the suction side of the circulator and the pressure side of the circulator. I was able to find a screaming vacuum leak tracing it back to the packing nuts on my steel compression tanks gauge glass and I tightened the packing gland nuts 1/4 of a turn and that stopped the vacuum condition.

You will be able to connect all three boilers 3/4" tapping of each Internal air separators to a single common 3/4" header that will reach the two steel compression tanks at the front of the tanks and install Tees to reach both airtrol valves at the proper slope to allow the warm water to rise to the airtrol valves and the warm water with the air bubbles will rise past the cold water that is dropping back into the water flow entering the supply piping.

If the steel compression tanks have tapping's in the front of the tank you can add Drain-O-Tank valves to make pushing the water into the tanks through the Airtrol valves quickly. The Drain-O-Tank valves will allow you to drain the tanks easier as well if the need arises.

Adding ball valves to the 3 risers to the common header piping that connects to the Airtrol valves will allow you to keep the water in the steel compression tanks if one of the boilers has to be drained as well.

Have you called Bell & Gossett to find out who the local representative is in this area that can help you with this design issue?