home made dhw system

larryp3

I have a weilmcclain oil fired hot water boiler with built in coil for hot water. Never have enought hot water. I was thnking of buying an electric hot water heater , and using it as a resovour, by ciculating water thru the w-m boilers dhw coil. I figure $300 for the electric heater tank, $100 for a ciculating pump and $50 for valves and piping. Would apprciate any comments on this idea. Thanks to all who repond.

Ed_26

dhw

Control strategy? - Tempering/mixing valve?

larryp3

figured on using the temp controler in the electric heater to control the circulator pump as i'm not using the electric coil.

Brad White_2

Common to do that

Providing that your primary submerged coil is in good shape (not full of minerals), what you describe is commonly done pretty much just as you suggest, using the tank controller to run the "shuttle" circulator. The best advantage, as I see it, has been to lessen the short on-off cycles inherent with rinsing out a glass or washing your hands. You draw off the volume and fire the boiler only during more prolonged charging times.

You could also use a SuperStor Ultra coil bootser made for the same purpose. Probably costs twice as much but will last longer being stainless steel. Nothing wrong with using a well-insulated electric heater though.

Weezbo

last i knew the anti- scald valve check and St-12...

would pretty much eat up that 50$ you have slated for the "Valves": portion of the job.

the numbers on the t-stat of the water heater wont control a breech in a coil...the anit-scald will at least keep the lid on it.

the option you suggest is done every day all over the world. the advantage in an indirect is that it has a dash more insulation...i Like insulation...

Eric Johnson

water heater t-stat

I've done that with a wood-fired boiler and it worked very well.

I'm wondering, would it work to wire the pump up to the surface-mounted thermostat on the water heater? When there's a call for heat, the pump kicks on. That way, it seems to me, you could avoid installing a tempering valve.

Weezbo

Eric, yes is the answer to your first question....

uh uh to the seeming observation...

the reason being, unlike the boilers high limit or auxillary additional high limit, you would have to have two zone valves on the supply side side to your hot and cold...even that would likely not be an answer to a breech as the valves would then also have to have a steam rating... AND a means to positively close them before the water made it that hot....200 degree water will cause you to look like a lobster in a heartbeat.

in a commercial application i would do a bit of research as to what is required. for appliances like dish washers or washing machines you are allowed higher temp waters...that way the clothes and dishes get hotter water...in a commercial operation the worker operating the washing wand needs to be protected from what he or she does not know....