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Hot water recirculator with a DSH, and a tankless

Last Post 03 Jul 2009 06:50 PM by jambsi. 6 Replies.

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jambsi

New Member

Posts:40

10 Nov 2008 11:50 AM
Help / ideas / opinions Overview: I'm trying to figure out how to take advantage of the 'free-in-A/C-season' and 'cheap-in-heating-season' DSH hot water to remove the pain of the 1 1/2 minute wait for hot water from my tankless hot water heater. Basics: - I'm in Canada = heating centric (7 months), cooling centric (coupla weeks), mama-bear perfect (4 months) - House is a conventional north design with full below-grade basement (finished), a long ranch-style with the mechanical room at 1 end and the 1 1/2 minute wait for hot water at the other. - Installing new plumbing lines and/or hot water pipe insulation is cost prohibitive. - I currently use a propane furnace (oink) and a propane tankless water heater. New: - I'm in the throws of installing a pond-loop (actually a river) geothermal with desuperheater (Climatemaster Tranquility 27 TT049) - The design calls for a non-wired electric hot water storage tank to store DSH heated water to be installed in series between the DSH and the tankless. Opportunity: - Cheap instant hot water, no water wasted! - There is hot water recirculators that don't require a return line eg: http://www.redytemp.com or http://www.grundfos.com/web/homeca.nsf/Webopslag/PAVA-53MKRN - How do I take advantage of the DSH provided hot water to recirculate in the hot water lines without trigering the tankless?

Ottawa, Ontario, Canada

hedgehog

New Member

Posts:51

11 Nov 2008 12:19 AM
i had a post in the other thread you posted this in, i to live in 'the great white north' as i described before i have a 3-ton with desuperheater that heats a 85gallon Marathon tank, the hot water output of that tank goes to the cold water input of a stiebel tempra 29, my goal is to hardly ever need the tempra. it does take a considerable amount of flow to make the tempra cut in, i would bet a recerculator wouldnt activate it, then even if it did, in theory it should for only a few seconds, until the hot water from the tank reach's the incoming water temp sensor, then it it would shut down, there is only 18" of 3/4 pex between my tank and my tankless so it would happen pretty quick, i have been thinking of doin the same thing. where abouts in canada r u?

joe.ami

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Posts:4377
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12 Nov 2008 07:47 AM
What you might find less expensive (with your contractor's cost compare software) is not using the propande water heater. Electric storage tanks are likely cheaper to operate and you can take the money you save and throw in a 1/2" return loop from the far end of the house (insulated). It will convect without a pump if installed correctly. There is little economy in solving with gadgets what you can achieve with pipe. Good luck, Joe

Joe Hardin www.amicontracting.com We Dig Comfort! www.doityourselfgeothermal.com Dig Your Own Comfort!

jambsi

New Member

Posts:40

12 Nov 2008 10:04 AM
Re: joe.ami "throw in a 1/2" return loop from the far end of the house". Thanks: I wish: - woulda, shoulda, coulda installed a return line. The mechanical room is at one end of a completely finished basement. Installing a return line &/or insulating the hot water pipes are not possible. Also, I already have the tankless propane so its installation cost is $0 vs some number of $hundreds for another electric tank + a 220V line, plus a footprint, so I don't think that's in the cards either. ----------------------------------------------------------------------------------- Right now the best solution looks like installing a http://www.redytemp.com/ recirculator at the fixture farthest from the mechanical room. The manufacturer reports that it will not work with tankless systems in that its "draw" it not strong enough to trigger the flow switch in the tankless hot water heater - which in my case is exactly what I was looking for. Therefore (I think) I will run the recirculator during heating/cooling seasons and get whatever the desuperheater outputs right to my faucet without the operating cost of trying to keep hot water lines warm with tankless output. In OTTAWA we have a 7 month heating season and hit & miss month of cooling season.

Ottawa, Ontario, Canada

Palace Geothermal User is Offline

Veteran Member

Posts:1609

12 Nov 2008 11:20 AM
Posted By jambsi on 11/12/2008 10:04 AM ----------------------------------------------------------------------------------- Right now the best solution looks like installing a http://www.redytemp.com/ recirculator at the fixture farthest from the mechanical room. The manufacturer reports that it will not work with tankless systems in that its "draw" it not strong enough to trigger the flow switch in the tankless hot water heater - which in my case is exactly what I was looking for. Please let us know how well this works. I am interested to hear the results

Dewayne Dean <br>www.PalaceGeothermal.com<br>Why settle for 90% when you can have 400%<br>We heat and cool with dirt!<br>visit- http://welserver.com/WEL0114/- to see my system

joe.ami

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Posts:4377
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16 Nov 2008 10:59 PM
After 20 years in my trade, one of the few things that still intrests me is the word "can't". I'll accept that it's not easy to install a return line, but even if you can't fish it or hide it, I still maintain that pipes (even with drywall repair) are cheaper than gadgets. Not saying this is you, but a common mistake of homeowners is deciding something is not possible before consulting the experts. Plenty of lazy contractors are eager to agree and charge extra for the complicated (vs the drywall) solution. J

Joe Hardin www.amicontracting.com We Dig Comfort! www.doityourselfgeothermal.com Dig Your Own Comfort!

jambsi

New Member

Posts:40

03 Jul 2009 06:50 PM
Update - a happy camper I have a conventional electric storage tank, which circulates through a Climatemaster 5 1/2 ton DSH. This DHW tank is turned on and set at 100F. The storage tank feeds a propane demand heater set @ 120F A http://www.redytemp.com/ recirculator is connected to the hot water line near the kitchen sink, which is about halfway to the end of the house. It has a return line to the DHW tank. The aquastat is set to 100F in the shoulder seasons & 120F in the heating/cooling seasons. The timer is set to come on during 'at-home-not-sleeping' times. So in shoulder seasons I always have instant or near instant 100F water, good enough for a quick hand rinse. The time to 120F has gone from up to 2 minutes to always less than 30 sec. everywhere. There are no plugs of cold water. No matter what there is always an endless supply of 120F water. When the DSH is kicking out lots of heat (Nov to Mar, July & August) the propane heate doesn't come on at all and I turn up the aquastat to 120F so I have instant hot water everywhere. Works great.

Ottawa, Ontario, Canada