Indirect Hot water system to steam boiler.

John_105

Hi all, 



  We are getting our Steam boiler replaced with a newer model, The MA heat inspectors surveyed our energy use and told us our old steam boiler is only .47 efficient, and that a new one would be .8... 

The company doing the work is recommending that we replace our 3 year old gas hot water heater and put in "ssv 45" 45 gall. indirect hot water system.  While it makes sense in the winter would this hot water heater be more efficient in the summer too?  Would our home heating system have to fire up just to Heat our hot water?  Would our steam radiators heat up in the summer too when this happens?

Is this a good product for us?

Jean-David Beyer

I wonder about systems like that proposed for you.

I am not a professional, but I do have an indirect-fired hot water heater attached to my hot water boiler. My boiler is very low mass (three quarts of water) and cold starts. In the summer, the boiler fires, heats the indirect, and shuts down a few times a day.



With a steam boiler, I imagine the same things happen, but there is probably more water in a steam boiler, so it will no doubt have to fire longer to heat the hot water. It should not get the water to the boiling point if the aquastat is correctly installed and set though, so it will not heat your house in the summer.



I do not know if people with steam boilers use them for indirect hot water in the non-heating season or not. I suppose it depends on the thermal mass of the boiler system to decide if it makes sense from an efficiency point of view or not.

John_105

Best application for indirect hot water?

yes it seems the Steam boiler would have to fire up, heat all the hot water in its own tank in order to heat the hot water for the indirect tank too.  So the heat left in the steam Boiler's tank  just disappears? Or is it insulated and contained until the next Fire cycle? 



It seems like there is a lot of potential for a heat loss... 



Is my situation the wrong application for an Indirect Tank or is there energy efficiency gains in the Summer months too?   Or do I gain so much efficiency in the winter that it makes up for any loss in the summer?



It might seem that indirect makes the most sense in the winter or in a situation where the main boiler is being used in the summer anyway? 

Jean-David Beyer

steam & indirects

I hope a real expert chimes in here.



For me, it makes sense to use an indirect even in summer because the mass of my boiler is so low and I can run it cold start. I do not know the figures for steam, but I imagine in the summer they are less advantageous. Whether they are bad enough to not use indirect in summer I do not know.



My system runs two or three times a day to keep the hot water heater satisfied, and usually runs for less than 10 minutes each time. So let's say it runs three times every day. Is your steam boiler insulated well enough to retain most of the residual heat for an 8 hour period? I used to have an old GE hot water boiler whose boiler was wrapped in some brown  paper and tied with string. This paper contained some kind of insulating stuff.  I think that was original. I cannot imagine it was very effective. But that was designed when heating oil was around $0.20/gallon, so maybe they did not care. It was always hot because it had a coil in it for hot water. The former owner did not use the coil, but I piped it in series with the electric hot water heater to take the chill off the incoming water at oil prices before running the water heater at electricity prices. I turned off that boiler in the non-heating season though.

John_105

In 4 Steam Boiler

So this is the New Boiler they would attach that to:  a Burnham IN 4...

http://www.e-comfortusa.com/products/burnham-in4sni-independence-electronic-ignition-steam-castiron-boiler-820105000-btu/2147



the specs say 6.5 gallons of water...  I guess they have some add-on to add the transfeir loop to the hot water tank or something?



Come to think of it, I would like to get some other installation quotes, are there any professionals in Boston that could install this system for me?

World Plumber

My $.02

     I would consider a tankless coil piped into the water heater. I think you said you have a gas water heater so I take it the boiler would be gas also. In that instance. Most manufactures have stop making gas units with tankless coils.

     I would choose to shy away from an indirect on a steam system to be used in the summer.  I might consider using the Brafordwhite with the secondary coil and use the coil to heat the tank in the winter then fire the burner in the summer.

      Considering the time to recover the cost I would go with the boiler and a separate Gas water heater.