steam and indirect hot water

bill_97

Peerless and Superstor Contender indirect . It's still running great . To keep the crud out of the circ as much as possible we mounted it up high in the water line of the boiler . The circ will have higher temps on it but it's rated to 240 degrees . A bronze circ is not a necessity . We come across regular 007s that have been on steam boilers for 10 to 15 years . And still running .

If you don't use a strainer , I'd suggest installing purge valves before and after the circ to periodically flush it out .

steve_173

Can anyone explain why almost every plumber I talk to says don't do an indirect with a steam boiler. The only plausible explanation I've heard is that the 220 water will damage the indirect over time and so it will not last. One also needs a aquastat to limit the boilers temperature in the summer so you don't get steam.

Is there any truth to what I am being told or is the indirect the way to go as has been suggested here?

How does one account for the BTUs used by the indirect or is a boiler sized by sq ft of radiation adequate for the indirect as well?

Since the indirect water temp will always be higher than the desired hot water temp, won't I have to adjust a mixing valve seasonally to keep a constant hot water temp? With a standalone hot water heater it seems it is more set it and forget it. I suppose there are automatic mixing valves as well.

Steamhead (in transit)

Some indirects

don't handle the nasty water coming from the bottom of a steam boiler too well. I believe the SuperStor is one that can.

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Tim Gardner

works for me

I have a steam boiler with an indirect. Works great.

The size of the boiler does affect the size of the tank that is optimal. A big indirect on a small boiler will give a larger hot water reserve, but it won't recover very fast and it may make more sense to just use a smaller indirect on the smaller boiler.

You usually size for either the total radiation and you don't add in the DHW demand. This is because you don't need DHW 24/7. The only downside is that if on the coldest day of the year you leave the hot water running, the house won't get warm enough.

The indirect water temperature might or might not be higher than the needed temperature depending on how you set the aquastat. If you set it higher than needed (in order to be able to supply more hot water), then you need a mixing valve on it. You wouldn't need to adjust this seasonally.

steve_173

How did you pipe it in? I was reading that you need a filter and then a pump further down line, but below the water line to prevent cavitation. Can this be done with all boilers? Do you think you have gained effeciency from the indirect? Is your boiler firing more than once a day in the summer?

With a mixing valave won't the cold water temperatures change seasonlly and thus need adjustment to keep the hot water temperature constant?

Are you suggesting what I was thinking that with and indirect one might not need as large a tank as with a stand alone water heater due to the high recovery?

Tim Gardner

I piped it according to the manufacturer's instructions plus a couple of extra valves. I oversized the pipe. I used a bronze pump with a wye cleanout right before it. The extra valves came in handy to purge the air on startup.

Basically it goes out of the boiler, drops to the floor, goes through the wye, through the pump up into a check valve, through the indirect, drops back down, through another checkvalve and up into the boiler. There are boiler drains and cutoffs everywhere.

The oil company suggested leaving temperature on the boiler during the summer, and it comes on and off maintaining its temperature even in he summer many times a day. The indirect pump also comes on many times a day to maintain temperature of the hot water. There are more efficient ways to control it but this way was simple.

Efficiency/savings is a tricky calculation because with the new indirect, my family takes longer showers using higher flow, so any savings are lost due to increased usage.

A thermostatic mixing valve maintains a constant temp regardless of the inputs, so there is no seasonal adjustment needed.

Yes, you don't need a big tank if you can recover it fast enough.

Unknown

I have one in my house

I used to maintain 10 college dorms that all had multiple indirects on big steam boilers, they work well.

I wouldn't put the strainer directly in front of the circulator, though. When it plugs up, the pump will have very little water flowing into it at close to steam temperature. Kiss the impeller goodbye, if you don't keep that strainer spotless. Usually, the bad water condition will be blamed, but what pump can run without water?

I piped mine like this

Noel