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tommie

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Posts:4

01/30/2006 7:45 AM
I'm glad to find this forum.. I've installed 3 equal loops of 1/2" pex in my new constuction Garage concrete floor..300' each loop....very simple. I did a heat loss calc for this location and have insulated the slab...etc... ok here's my question(S).... My local guy told me to use TWO pumps, a hot/cold mixing valve and of course the expansion tank with an air scooper/bleeder. I'm using a Domestic Water Heater for now. He also advised to take the hot water out of the tank not from the top but somewhere else as to help eliminate air buildup..I understand that .. can I switch the thermal blow-off valve on the tank and the "HOT" outlet?? Or Can I use the bottom boiler drain for the hot out? the latter is what I'm doing now and have a boiler valve on the top "HOT" outlet for bleeding purposes. OK now can't I just use ONE PUMP???? I'd like to keep this simple.. I already have it hooked up per his napkin drawing but it's not circulating well at all.. His diagram shows the cold water return after my manifold teeing off 3 ways one side returning to the tank another branch to the water mixing valve then another with a secondary pump circulating water 24/7 and the main pump taking mixed water from the mixing vale and switched by a line thermostat or controller for demand. I'm having trouble with it flowing.. does this all seem right or should it be a heck of a lot simpler.. It is merely a closed system in the garage with NO other water in or out!! thanks in advance and sorry for the rant!! ALSO should the pumpp (S?)? be lower than the whole deal or anywhere??? they are Grundos circulators. tom

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01/30/2006 10:07 AM
Not sure I see why yours is so complicated I run off hot water tank -- top -- split to domestic water & to floor unit obviously lower than tank top . An expansion tank is installed also On the way to the floor I have an air trap at highest point and then drop to a Grundfos pushing into a single floor water coil. The discharge from the pump is split & ties into the domestic water forming a loop with the line off the original split. The original line has a check valve to avoid short circuiting back to the tank caused by the pump generated pressure. The domestic hot water ( after second split ) runs past all the taps and back to the cold side of the tank with a check valve & a restricting valve nearly shut. This gives me "instant" hot water at all the taps when the pump is running & gives air a route to exit as taps are upstairs. They are all marginally hot from thermosiphon action even with pump down. We really like the instant hot feature. The lines are insulated so heat loss in summer is very limited. I suspect your poor circulation has to do with three parallel loops where one or more is hogging the flow due to an air trap in the other lines . Can you individually restrict the flow ( even turn off ) to push air out? -- I had trouble with circ initially with no air trap but now NP's. It doesn't have to be complicated with two pumps ????

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01/30/2006 10:39 AM
Thanks for the reply! I can shut off each loop individually.. both manifolds have ball valves for each loop..in and out. I have no air in the floor.. I just want this as simple as can be.. and need no Domestic hotwater for taps..it is simply in the garage to heat the floor!! I don't see why I just cant use one pump off the tank hot side and then thru the supply manifold , thru the floor loops, then from the return manifold back to the tank??? The expansion tank couldgo anywhere in the system, but the instructions said to place it in the cold water line to the tank not the hot side.. any thoughts?? thanks again in advance..tom

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