I have recently completed a bathroom and activated the geothermal floor heat. Unfortunately after 5 days I am not attaining much warmth in the room. I have raised the floor temp from 60F to 69F at the beginning of the floor coil and 66F at the end and the overall room temp is about 61F. My input water temp is about 100F. I fear that I do not have sufficient 5/16 tubing in the floor. The contractor who designed the floor system specified Uponor Quick Track. By the time I avoided the vanity, tub and shower space all I managed was about 75 feet of 5/16 tubing. Any contractors out there who can suggest how much tubing I should have had. I have jacked my tank temperature up to 104F. If I can attain that I'll try another degree. I also have about 35 feet from by manifold to where the tubing enters the bathroom. I am also going to insulate that run and see how much that helps. Unfortunately I am not going to tear out the bathroom to add more capacity so I may have to live with insufficient heat or add a supplementary heater. Any suggestions or comments will be appreciated. FYI I have a ClimateMaster 5 Ton Tranquility and a 120 gal. storage tank. The radiant heat in the basement floor is 1/2 tubing and produces sufficient heat with about 6" spacing on the floor loops (the bathroom is 7" spacing of 5/16 tube).
Your slab temp is too low, as you've noted. Now why that is low is hard to determine. Ideally, we need to know the heat loss of that zone (the bathroom). Then we can figure out the heat flux required into that space to heat the room. But you need to start seeing slab temps in around 75F to get the feeling of heating that space. The fact you are losing 20F through that piping, suggest you are dumping heat somewhere. At 2gpm, you are dumping 20,000 btu's in to some space. Note - not checking math as my littl'un is yelling at me to take him over to the neighbour's haunted house.
Thanks for your reply. When you mentioned dumping heat somewhere I realized I left out an important piece. When I activated that zone it also includes my 9' x 11' foyer covered in slate. Didn't immediately think of this because it picks up heat from the main Water-to-air system. I did check and those tile too are sitting at about 68F. I agree with you, I figured if I wanted to get 71F in that bathroom I had to see slab temperatures at or above that temp. I do suspect that I am losing some heat in the run from the manifold to the point of entry into the floor and will be insulating that run; hopefully it helps a bit.
Thanks Chris. Airlock did seem the most obvious to me. I have beled the heck out of itwith no obvious air. I have also shut it down a few times hoping any air would settle in one place and be easier to bleed out but with no apparent sucess. The system has been running for about a week. I have an Axiom auto-filler and a purge tank. I would have thought any air would work itself out by no but I could be wrong and still have an air lock. Any suggestions on what I might do further or just try more of the same? By the way, after my last shut down last night, when I restarted this AM my return temp was 70F vs. 100F input. After an hour or so the return temp was back to 80. Again, Thanks Bob
Flow does seem limited but I attributed that to the small tube diameter (5/16"). The bathroom circuit is about 75'. The Foyer is about 140'. The main circulating pump is a Star 21FX and each zone is controlled by an ECO16F
If you have 30F difference between supply and return, you do have almost no flow, and you loose the heat somewhere. In low temperature applications, like geo, the floors should have a delta T of less than 10F, most of our floors are running a delta around 5F.
Doc, thanks for your input. It would appear that my delta T at the best of time is about 20F. When the floor is cold, as in after a shutdown, that climbs to 30F. I agree it should be much lower as what this indicates to me is that the water is giving up heat rapidly, so much so that by the time I am 20 feet around my room there is nothing left to heat the tile. This would seem to be borne out by the fact my bathroom floor is 71F at the beginning of the loop but only about 68F at the end of the loop. The same pattern can be seen in the foyer. Now I do have fairly long runs from the manifold to the point of entry into the floor. Although these runs are through heated space I am pretty sure that is where I am giving up a lot of heat before I even reach the floors. I do need to insulate these runs and would appreciate any advice on a product to use that will stand up to the heat and if it is a good idea to wrap both the input and return lines together or keep them separate. I realize the input could give up heat to the return line but maybe if the differential (delta T) is low enough it wont matter. Any advice from you folks will be greatly appreciated. There are many times I wish I had local access to the kind of expertise that exists on this Forum but unfortunately when you live out in the boonies you just can't find the expertise. Again, thanks for your insights.
Unless you have some "overheated" space in your house, I would look at increasing/improving that flow prior to worrying about insulating those lines. You may end up doing both, but there is something off with your flow that insulation won't fix.
Any suggestions on how I can verify my flow. Opening the return bleed line produces almost a gallon in about 30 seconds. Admittedly this does not seem like much but that is measuring through a 1/4" bleed line. It may be representative of what is flowing through each 5/16 loop, I don't know. The flow meter on the manifold reads 0.2 or maybe that's supposed to be 0,2 my tired old eys can't tell. The manifolds are Uponor EP Thanks
The flow meter could be stuck - I usually just tap on them to verify. Also, see if you can open up that zone valve more. I don't know Uponor specifically, but should be a way to open up that zone on the manifold and increase flow. Also, may be obvious, but make sure you have the correct circuit. I've seen them mislabeled. Controls going to wrong zones. And so on.
Once again, I appreciate your taking the time to offer your expertise. To go backwards on your message, I definitely am looking at the correct manifold and controls for that zone. Even if they were mislabeled because this zone is above the control board it is easy to visually confirm things. There is a flow meter with a control valve on the inlet side of the manifold and it is wide open. No amount of tapping is making it budge. One thing I have noticed it that there is an air bubble sometimes at the top of the flow valve. Bleeding the manifold usually makes it go away but the max flow I am able to get is 0.2gpm or as I said before, maybe that's supposed to read 0,2 gpm. Assuming it is 2gpm is this a normal flow for a 5/16 loop? Because everything would seem to point to an airlock I tried purging the loops but although I seemed to be getting pure fluid nothing has changed. I was using a small pony pump so I could be running a glycol mix into the loop but I wonder if the pump may have been introducing air. I am going to try and do this again this time hooking the manifold up to the water tap. That will dilute my mix a bit but I should be able to remedy that.
O.K. I was way off on my initial assumption. I had "assumed" 5/16 was really just a typo - and you meant 5/8th. Now, I googled 5/16 PEX, and it is something made specifically for the Wisbro/Uponor stuff. I haven't come across this in the wild. I ended up making some assumptions based on this. Like 2 gpm. So starting over, 5/16 is smallest diameter PEX pipe I've heard of, and looks like I can't find a flow chart/pressure drop table for this. When you close off all zones, the best flow you get for this is 0.2gpm?
Definitely 5/16"; pretty small pex, seems to be made for their Quick-Track system. With only one port open on the manifold the best I can get is 0.2 gpm. The maximum on the flow on the gauge is 1.0 gpm. For comparison I looked at one of my basement floor zones. This zone consists of 4 loops of 1/2" PEX on the same kind of Uponor EP manifold. These loops are balanced out at .4gpm and seem to be working fine i.e. after startup the thermostat reaches the set point in a reasonable time. Again, thanks for your input.
Bob: Hello and welcome or welcome back. How long is the total length of that 5/16"? Do you have Uponor numbers for pumping and max lengths for this product? I use the most cost friendly manifold, most are made by the same guy. I have seen manifolds with flow controls on the discharge and return connections. You should be able to make sure both sides are wide open without dumping the floor. Re-read the I/O manual about flow adjustment. Mark
Mark, Thanks. Everything is well here. The geo system is keeping us warm and cosy and hasn't presented any real problems until the recent addition to the system. To answer your question the one loop is about 75' and the other loop is about 200'. This includes the run from the manifold to the point of entry into the room. I realize the one loop is pushing the limits for 5/16" but heat in that area is not critical. I'm pleased to report I think I have the problem licked. Each of my zones is controlled by a variable speed Wilo-Stratos ECO pump. The first 4 zones are 1/2" Pex and all below the level of the manifolds. This last zone is 5/16" Pex and above the level of the manifolds. Urthbuoy gave me the idea and it struck me that the factory default for the pumps is about 3' of head. I cranked that up and managed to get sufficient flow (0.4 gpm) to reduce my dela T from 20F to around 12F and I'm finally getting some heat into the room. Again thanks for your interest and suggestions. Take care.
