Tempering valve.... heat trap??

[greg273]

I'm installing a tempering valve in a solar/wood fired water heating system. The instruction sheet says " Mixing valves at or near the heat source should be trapped to reduce mineral deposits, reduce convective losses and reduce component wear".

I'm not so sure what they mean by 'trapped', my on-line research so far seems to indicate that this is neccesary when the mixing valve is HIGHER than the heat source, because hot water will rise up to the valve and wear out the thermostat quicker.

Well, if anyone has any idea what a 'heat trap' is, please let me know!

thanks,
greg

[agmantoo]

My awareness of what you are attempting is certainly limited. That said, are you certain that you need a tempering valve or would you be better served with an anti scald valve. I would think you need to hold the water as hot as possible in the storage area to extend the amount of hot water available.

[Theront]

My experience with "trapped" is a little screen in the line to collect the large minerals and solids. We use these inline on a lot of cooling systems and have one on the tempering valve of a hand sink..

I don't know if this is what you are looking for.


Theront

[BD]

hi, its hard to interpert without seeing the installation manual but i think they want you to maintain a trap in the piping so it will have water in the line at all times . This would be like the drain on sinks. Pipe out of unit, drop down , and then back up. I think they are trying to prevent false readings to the valve so piping will always have water in it and heat by conduction or convection will not affect it. BOB

[mtman]

they might be talking about a trap and straner used on hot water pipes and allso steam lines go to the plumbing supply tell them what size pipe you are using http://www.fusionworldwide.net/bornze-thermodynamic.htm it is a pipe fitting that looks like a Y

[Jackpine Savage]

Greg, I ran across this in a plumbing book awhile back. I'm not sure that I can describe it well but it's a loop of pipe that will prevent thermosiphoning within the pipe. I guess its actually a good idea to put heat traps in the input and output lines of all water heaters for energy efficiency. For a water heater the pipe would go up, then down 6-12 inches, and then go back up again.

At the end of this Watts PDF they show some examples: http://www.watts.com/pdf/PG-MXV.pdf

[Ross]

I'm no plumber but I've seen as described, the "U" shape piping on the output to prevent thermo syphoning. Can't say I've seen it on the input pipe and you don't want a restriction there making it a closed system but a "U" piping layout would still allow for expansion I'd think. Any plumbers out there?

[Jackpine Savage]

My BIL has been a plumber for about 5 years and when I ran this by him he hadn't heard of it before. I did another search and they are also referred to as anti-convection traps. Here's another PDF that shows the traps installed on the input and output of the hot water heater: http://www.energy.iastate.edu/homese...terheaters.pdf

The traps are just open pipe so there isn't any pressure restriction.

[Ross]

The traps are just open pipe so there isn't any pressure restriction.

That's how I see it too, might help keep the heat where it belongs or might be over kill, it'd be cheap enough to try though. I know you don't want a one way valve in there blocking the hot water from moving cold back into (against) the presure system in a DWH; it needs that expansion room.

[mtman]

the loop you are talking about is a hartford loop it keeps hot water from traveling up to far

[Jackpine Savage]

Originally Posted by mtman

the loop you are talking about is a hartford loop it keeps hot water from traveling up to far

To me it looks like the Hardford loop is for Steam Boiler returns:

http://www.heatinghelp.com/newsletter.cfm?Id=91

[mtman]

it is allso used comming from the coil feeding the mixing valve

[BD]

hi, the hartford loop I belive was started by the HARTFORD INSURANCE COMPANY back in the old days when steam was the primary heat source.Normally it was only installed on gravity return steam systems.This connection provides positive protection against emptying the boiler.
The Hartford connection is an inverted seal in which one or more returns are header together below the boiler water line. It is a crossconnect from boiler steam header to boiler return with the center of tee 2 to 4 inches below the boilers normal water line .This tee then has a close nipple in it with elbow facing the floor and a piece of pipe with another elbow or tee on it that will extend below the boiler return connection.

[mtman]

from the center of the coil to the center of the first 90 is a 24 in. piece of pipe then again im used to working on boilers that staned 18 feet tall

[joken]

I have installed many of them. Install it however you want as long as the connections are correct. Ken