Welcome to GreenBuildingTalk - the place to share, ask and learn about green building products and methods. While you can browse the site as a guest, you need to register in order to post. Registration is fast, simple and free so join our community today.

Unanswered Active Topics Forums Search Members

You are not authorized to post a reply.	Prev Next
Author Messages Oldest First Newest First ergnut Registered Users Posts:14 04/30/2008 4:57 PM   I'm not seeing a direct answer to a question I've had, which is: If I've got a standby tank that is heated using geothermal (which will max at 130 degrees f, but works more efficiently below 120 degrees f, can I use an an electric tankless to boost the temp from about 110 to 120? The tankless manufacturers always quote the rise in temp that a unit will supply (ie x gpm at input temp of y and output temp of z), but I'm interested in knowing if the input temperature of 110 would cause a problem for a tankless electric system?  I've seen a max input temp listed on the Stiebel Eltron heaters of 107f, but I've not seen figures for other brands?  Would I need to be careful not to oversize the TWH if I'm only interested in a 10 degree jump at 3 - 4 gpm? I'm interested to hear of any first hand experience in using a tankless system this way. Thanks Brock Registered Users Posts:134 04/30/2008 9:34 PM   I did that in our last house and it worked OK. The big problem we had was as flow changed the temp changed. Some of the newer ones are better at regulating temp, but they typically come on in 5kw or so increments. As you noted some won’t kick on if the water temp is above a certain temp. Ours was about 110F and that was all the way hot in the shower so it worked ok. If I had to do it again I would get a small 5, 10 or 20 gallon electric depending on usage and put that after the geo tank. It won't care if the incoming is 130F or 55F and be pretty close to the same efficiency if it's small and insulated well. Green Bay, WI. - geothermal heated indoor pool with a small solar setup
You are not authorized to post a reply.	Green Building Forums --General Forum - Residential --General Forum - Commercial Green Building Technologies --Insulating Concrete Forms (ICFs) --Structural Insulated Panels (SIPs) --Radiant Heating --Geothermal Heat Pumps --Solar and Wind Power --Windows/Doors and Interior/Exterior Finish --Appliances, Lighting and Kitchen/Bath Fixtures Green Living --<a href="http://discuss.greenoptions.com">Green Options</a> Feedback/Support --Rules, Instructions and Announcements --Suggestions/Feedback --Testing Area
Forums > Green Building Technologies > Geothermal Heat Pumps > Use of Tankless Electric to Boost Preheated Water?

ActiveForums 3.6