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Water level for tankless coil with autofill?

Jim Franklin
Jim Franklin Member Posts: 170
Hi folks...I rented a house with a Peerless JOT-TW (TW-3) steamer and Mconnell & Miller 47-2 cutoff/feeder combo. I've never had an auto-fill system before. My problem is lack of domestic hot water. If the heat has been on, the water is ok for 5 mins, then gets cooler as I chase it by throttling the cold water valve in the shower. After 10 mins I'm showering with the hot valve only. If the heat hasn't been on I get tepid water from the get go.

It has a L4006a set at 180. The mixer works, in that I can feel the mixed pipe changing temp, but it never gets hot enough. Feels like the incoming hot isn't hot enough.

The water level is about 1" from the bottom of the sight glass, which means about 75% of the coil is covered. Should I increase the water level? If so, is it adjusted at the auto-fill or is that just protecting the boiler with a minimum level, and I need to manually add water like a non autofill system?




  • World Plumber
    World Plumber Member Posts: 389
    Water line

    Is there a mark for the water level on the jacket? Most of the JOT's were in the middle of the sight glass.? Is there a flow restricter?

     Welcome to the world of tankless coil. The hotter the boiler the hotter the water you have to start with and the more you get. Common complaint.
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