I don't want to mess with Rob, but I'll still vote for the 7 gpm coil. It is a few more $ up front, but I think its larger surface area would let you produce any given DHW flow rate with a lower boiler water temperature, so you'd save on standby losses. And it provides extra capacity in case you want to run the dishwasher or laundry, have people take showers, or carry whatever other DHW loads you have. Plus, it was the original equipment spec'd by EFM for 700's, and is called for under the Massive Overkill Doctrine to which I subscribe.
Mike
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- Rob R.
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- Location: Chazy, NY
- Stoker Coal Boiler: EFM 520
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I was trying to be cost sensitive. If the funds are available, use the 7 gpm coil. If even more funds are available, look at an indirect.
This boiler is in a remote building, so I assumed there would not be additional DHW load during the pressure washing.
This boiler is in a remote building, so I assumed there would not be additional DHW load during the pressure washing.
- Scottscoaled
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- Coal Size/Type: Lots of buck
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Boiler is in attached mother of all god garage.
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Yes the water is hard but it has not been a problem with my appliances and we built the house in 1997. I am going to try the coil. I am going to mix the water at the spicket. I am going to use 3/4 in and out for the coil.
- lsayre
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I would add a proper mixing valve so you don't get scalded. There are several good brands. This is the one I have:
http://www.pexsupply.com/Taco-5003-C2-3-4-Sweat-5 ... xing-Valve
http://www.pexsupply.com/Taco-5003-C2-3-4-Sweat-5 ... xing-Valve
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I ran the hot water from the DF520 7gpm coil to a Marathon 85 gallon hot water heater as a big capacitor. Works great even with the Marathon heating element off. My wife says this is the best space capsule I have ever bought since it keeps her soaking tub filled with hot water. No more angry faces or threats to replace my DF520 boiler(or was that me?)! Coal just takes too long to heat up to keep up with lots of domestic hot water. When its on oil its fine, but not on coal. Takes a while to get the coal nice and hot!
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To handle big DHW loads with a coil you need to make sure the feed/air rates and low temp limits are set accordingly. In our old house we used a coil in an EFM 900 and it made infinite hot water for a family of 8 without breaking a sweat.
Mike
Mike