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[hondaracer2oo4]

Radianttec.com has lots of good info opunder their resource page. Just overlook the info about them trying to push their products.

[shepherd boy]

wreckit87, don't follow you about using a 3-way zone valve in a infloor set up. I never do that. am I missing something?

[wreckit87]

wreckit87, don't follow you about using a 3-way zone valve in a infloor set up. I never do that. am I missing something?

Let's say your boiler loop runs through the house, hypothetically hitting a DHW plate exchanger first, then a forced air coil, then catch the radiant basement floor on the way out. If using the main boiler pump to circulate everything, including the radiant, there is no way to direct 2/3 of your water out the branch of the tee and through the floor when the straight shot back to the boiler is free for the taking as the head loss in any floor is more than a straight run to the boiler. In this situation, you'd need a 3 way zone valve to direct all flow through the floor while the main loop gets nothing but 60-80 degree floor return water; we know how good that is for the boiler. That's how most of the clowns out here do it anyway, which slows down the primary boiler loop to whatever GPM can be shoved through the floor loops. Another option being a 4 way mixer to keep both the floor temps and boiler return temps at a happy(ish) medium, but the cost of that mixer is considerably higher than closing the system. A secondary zone pump for the floor in addition to the primary boiler loop pump is an option that I overlooked at first and RSI corrected me, which would eliminate the need for a 3 way ZV. That's how I see it anyway.

[wreckit87]

Thanks for all the information, looks like I have missed a few steps in my system design. What will happen to my concrete with current setup?

First off, running high temp water throws a HUGE amount of heat into the concrete, which we know is a very big heat sink. A wall thermostat, which most folks use, will satisfy when the air temp reaches the setpoint. When that happens however, the slab is usually too hot to stand on which in turn continues to radiate heat into the room well after the pump stops, and overshoots the setpoint. Let's say setpoint is 70, but the air temp gets up to 75 because the slab is so hot. After this, it may take 18 hours to get the air temp back down to 68 or wherever the stat kicks the pump back on- at that point, the slab is cold again and you start all over. You want the water to be the bare minimum temperature. If it circulated constantly but maintained air temp would actually be the most efficient system possible, which is almost achievable with the use of outdoor reset. A typical floor runs 90-110 degree water depending on load and desired air temp. This keeps a more constant slab temp which keeps a more constant air temp. Also, the constant hot/cold cycles of running high temp water destroys concrete and cracks the piss out of it.

[shepherd boy]

  Yes, I just use two tees close together with a mixer and a pump. Less restriction on main line than a flat plat. It's all on a secondary loop. Just had never heard of or conceived how you used a zone valve in a infloor setup. Hate them zone valves anyway. Try to avoid them.

  Slimchance, you probably won't hurt your Hardy but it's going to burn a lot of wood dumping direct in floor and it's not good for your floor. Cheapest and easy way out is a mixer and second pump. Put the secondary pump on a stat. Do your garage the same way. Have a stat for each. Using a flat plat will work too but is more involved. Sounds like you are doing this yourself and the simpler the better?

[E Yoder]

I think we all agree the floor loops need to be mixed down to approx. 80-100℉ and hydraulically separated from the main loop either using a flat plate or close tees (or some other method)? The floor loop flow shouldn't affect the primary loop flow. With close tees the secondary loop can recirculate some water if needed. With the mixed down temps the close tees are only sipping off 1/4 of the gpm of the main loop in comparison to the floor loops. Most floor water gets recirculated and never hits the main loop.  If it's the last load on the primary loop it won't affect the other loads like DHW or fan coils.

 I've always used a secondary loop pulling through the mixing valve. Using a three way zone valve and using the main loop pump would choke flow as wreckit said and the mixing valve needs equal pressure on hot and cold inlets which it won't have pushing in the hot.

And I don't say any of this to argue, I just love hashing hydronics. Hope you guys understand.

[wreckit87]

I like this guy! ^^^^ I hope I'm not coming across as a jackwagon by being stern and asking silly questions- I have no intention of starting an argument either. The main thing I'm trying to push with radiant is to keep the oxidation and sediment out of the slab, which is present in an atmospheric system regardless of how much you filter your fluid. Your available BTU will transfer more efficiently as a closed system as well. I mean, you can keep your truck on the road by just changing the oil and not the filter, but is it right? It'll keep you moving for now and work okay, but after awhile the filter plugs with shavings and you spin bearings. Same thing happens in radiant floors. Does atmospheric radiant work? Absolutely. Is it as efficient or bulletproof as pressurized radiant? Not so much. There is a reason every radiant designer in the world specs oxy-barrier tubing- because a correct system should be oxy-free. You buy the pump and mixer anyway to run it atmospheric, what's another $225 for a plate exchanger, air separator, expansion tank, and relief valve to have a worry free system that'll outlive you? Minimal upfront investment to have a proper heating system over one that just works in my opinion, but it's merely that: an opinion. My local plumbers have made me a lot of money over the years by installing poorly designed systems, so I'm really okay with the job security 

[E Yoder]

I like this guy! ^^^^ I hope I'm not coming across as a jackwagon by being stern and asking silly questions- I have no intention of starting an argument either. The main thing I'm trying to push with radiant is to keep the oxidation and sediment out of the slab, which is present in an atmospheric system regardless of how much you filter your fluid. Your available BTU will transfer more efficiently as a closed system as well. I mean, you can keep your truck on the road by just changing the oil and not the filter, but is it right? It'll keep you moving for now and work okay, but after awhile the filter plugs with shavings and you spin bearings. Same thing happens in radiant floors. Does atmospheric radiant work? Absolutely. Is it as efficient or bulletproof as pressurized radiant? Not so much. There is a reason every radiant designer in the world specs oxy-barrier tubing- because a correct system should be oxy-free. You buy the pump and mixer anyway to run it atmospheric, what's another $225 for a plate exchanger, air separator, expansion tank, and relief valve to have a worry free system that'll outlive you? Minimal upfront investment to have a proper heating system over one that just works in my opinion, but it's merely that: an opinion. My local plumbers have made me a lot of money over the years by installing poorly designed systems, so I'm really okay with the job security 

thanks, that makes sense. I enjoy the discussion.