Questions about radiant heat system

[CalG]

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[mx842]

You know what?????? This isn't fun anymore. Well maybe still a little but this thing is driving me nuts. I spent all day yesterday and until 4:30 this morning re-plumbing the manifold pump and a few other things at the manifold and I still cant get those flow meters to show anything. The little red disk is stuck right at the top and won't move. I took a couple of the flow meters apart and cleaned them looking for something that wasn't there. Put it all back together and still the same. I've back flushed, front flushed, sideways flushed and it still seems to have air somewhere. I changed the way I had the pump plumbed and it seems like it was a little better but there is noise in the lines like water trickling down a little brook then I notice the pressure needle going up and down 3 or 4 lbs and the noise seems consistant with the pressure movement. I know there is some flow going through the loops because I can take the loop end off at the return manifold and there is water flowing but it just wont move the meter. I'm about ready to pull all that mess out and buy and new manifold.

When I bought the manifold they didn't have a 8 loop one so I had to get a 5 and a 4 loop one and connect them together. I was pouring the floor so I had to do something. I don't know if that may be part of the problem but the guys at pex universe said it should work fine. I don't know, I guess I'll leave it for awhile and hope it works itself out.

 

[CalG]

You know what?????? This isn't fun anymore. Well maybe still a little but this thing is driving me nuts. I spent all day yesterday and until 4:30 this morning re-plumbing the manifold pump and a few other things at the manifold and I still cant get those flow meters to show anything. The little red disk is stuck right at the top and won't move. I took a couple of the flow meters apart and cleaned them looking for something that wasn't there. Put it all back together and still the same. I've back flushed, front flushed, sideways flushed and it still seems to have air somewhere. I changed the way I had the pump plumbed and it seems like it was a little better but there is noise in the lines like water trickling down a little brook then I notice the pressure needle going up and down 3 or 4 lbs and the noise seems consistant with the pressure movement. I know there is some flow going through the loops because I can take the loop end off at the return manifold and there is water flowing but it just wont move the meter. I'm about ready to pull all that mess out and buy and new manifold.

When I bought the manifold they didn't have a 8 loop one so I had to get a 5 and a 4 loop one and connect them together. I was pouring the floor so I had to do something. I don't know if that may be part of the problem but the guys at pex universe said it should work fine. I don't know, I guess I'll leave it for awhile and hope it works itself out.

Quit dick'n around with the entire manifold and multi circuit loops. Get ONE LOOP to work, then move to more complication.
There must be something, some detail you are missing.

 

[Raspy]

Maybe you could take a few pix and post them of the setup you have. The noise you describe sounds like surging air. It can be frustrating at times.

 

[quicksandfarmer]

Quit dick'n around with the entire manifold and multi circuit loops. Get ONE LOOP to work, then move to more complication.
There must be something, some detail you are missing.

This. Divide and conquer. Break it into the smallest possible units, if possible things you can assess visually. I'd cut out the circulator pump and hook it up to house water and see if you can get flow through.

 

[mx842]

Quit dick'n around with the entire manifold and multi circuit loops. Get ONE LOOP to work, then move to more complication.
There must be something, some detail you are missing.

I'm not sure what you mean by multi circuit loops. I can shut off every loop but one......any one and the flow meter still doesn't move. I know there is water going through them just don't know how much.

 

[mx842]

mx,

Regarding plumbing the HX to the water heater: The HX is horizontal and it doesn't matter which line is in or out, but plumb the out to the top of the tank with as little restriction as possible and an up-slope all the way. This will help the thermosyphon affect and, during a power failure, will circulate some water. Assist it with a pump to get the maximum BTUs to your tank. The 007 should be fine for this duty. Use the 3/4" port on the side of the tank near the top, typically, this is the pressure relief port, as the return from the HX.

TEE the output to your floor pump at the same upper side outlet of the tank, where the HX line ties in. Simply screw a brass or galvy tee on a short nipple sticking out of the tank fitting and plumb each line to it. Return the floor loop to the cold inlet on top of the tank. Pull the dip tube out of the cold inlet fitting and set it aside. Put an automatic air vent on the hot outlet. If you insist on an auto fill system, tie it in at the cold tank inlet with another tee.

I suppose the best flow pattern would be to place the HX pump on the bottom line pumping away from the tank toward the HX. Place the floor on the line from the upper side fitting tee, pumping toward the floor. Return it to the cold top fitting as mentioned.

All of this will tend to move air to the tank and get it out of the system. It will not inhibit thermosyphon.

Install tees on the supply and return lines to the floor. One just before the pump, which is pumping toward the manifold. And one after the manifold on the return line to the tank. Connect these with a 3/4 pipe and a ball valve. This will allow you to throttle a bypass and control the supply temperature somewhat. It also reduces restriction in the floor loop. You'll still get all the available energy to the floor, but you'll avoid scalding temperatures and you'll help the pump purge the air. A bit of manual adjusting of this ball valve will get you find the right setting. Probably 1/2 open for starters.

Install a ball valve on the return line to the tank from the floor. Preferably, near the tank. Then tee in a hose bib right before this valve (on the manifold side). You can then close the valve and open the bib to manually purge the floor loops. This will help you get it all started and force out any air.

Again, look carefully at the manifold to make sure you have the loop restrictors fully open. Very important.

I went back and looked at this again and am a little cornfused :confused2: I installed a tee just before the isolation valve going into the tank. Is that to let water in or out of the system? If out, where would you dump new water into the system to get the most air out while purging?

 

[mx842]

Also I added tees between the supply and return with a valve in the middle. That seems to be working as you described. The only thing is I didn't have room to put a tee before the pump not enough pipe coming out the wall so I had to put a tee after the pump about 10" before it enters the manifold. Space is tight in that area by design. I mean this is a small office area and I wanted to be able to have all this equipment in the wall with a sliding door that would cover this mess up and also keep it protected from inquisitive hands and other traffic in the area. I guess I could have done the same thing over in the boiler room and would have had more room to work. I want to re-run the way I have the manifold return line plumbed into the tank anyway. Would I get the same effect putting the tees in the boiler room as at the manifold?

Right now I have the manifold return water entering into the tank at the bottom drain port. As I mentioned before somewhere the way that side is plumbed now is manifold return teed into the bottom with a drain valve out the straight part of the tee. Supply to the manifolds (1" port ) where the upper heating element was. The return to the HX I have coming out the lower 1" heating element port. And the supply from the HX to the tank goes into the top 3/4" port where the T&P valve was. I didn't have room the way my setup is to pump into the HX so it's on the return to the tank out of the HX. The aqua stat I put in to control the 007E pump works great for the time being I have it set to turn the little pump on at 160 and it goes off at 140. I have another aqua stat I want to put on the line right where it comes out of the 1" supply port at the tank set at around 110 to turn on the circulator at the manifold. If this works out I want to get another aqua stat with a differential lever on it so that pump can run longer. I haven't run the wires over to the manifold yet for this to work but will do so soon, I just want to see how this aqua stat I have works before I do buy another one.

I was wondering if I could use the old oil burner and circulator control I have to do both. Say use the burner side to cut on the 007 and the circulator part to cut on the bigger pump? It's just a thought I was kicking around.

 

[Raspy]

For some reason, we still haven't solved the basic problem of getting the air out and getting good flow through the loops.

Your system looks like a figure 8 with the tank as the center of the 8. It is the X part of the 8. If you simply valve off one side of that 8, the manifold side, on both sup and ret lines, then add tees next to the valves, you can flush that side of the 8. Flush both pipes, the pump, the manifold and the loops all at once.

Remember, the center of the figure 8 is an X, That is where the tank is. It's the X. The supply line comes from the X and goes to a valve, then a tee (tee 1) then the pump and then the manifold, then the return line comes from the manifold back to another tee (tee 2) then another valve and back to the X (tank). Both tees have hose bibs, or tee 1 has the auto fill instead. The flow goes toward the manifold hot side, or red side. I don't know if your flow meters are on the supply or return (hot or cold) side. Watts manifolds have them on the hot or supply side.

Now, fill the system (manifold side of the X) at tee 1 with your auto fill. Then close both valves and open tee 2 hose bib to purge the air out of the pipes, the manifold, the loops and the pump. Done.

Or, with no auto fill, connect a hose to tee 1 with a bib instead of the fill valve and use city pressure to blast the system out. Auto fill is better.

Now, open the valves, close the bibs on the tees and start the pump. System pressure should be at 10 to 20 PSI to begin. Static cool pressure later should be set a 12. If air gets into the pump again, open tee 2 hose bib while it's running to force the air through the pump. You can close the supply valve with the pump running to help with this process, if needed. With no air, and the loop restrictors open, and the flow in the right direction, you should be seeing about 1 gpm at each flow meter and the pump will be quiet.

Maybe your flow meters are simply stuck and you are getting flow. Could be. With everything running and most of the air out, slowly close valve 1, before the pump, and listen to the pump as you do. Does it's sound change? If so it's probably pumping. If it's pumping you have flow in the loops. It's sound may change with pockets of bubbles going through it during the startup process. Listen for this. A grinding sound that will come and go. That's good. It means it's working. Once it's working it will clear itself completely over time and become silent. It's performance will also increase and you'll see a higher flow rate. A steady grinding sound probably means it's air locked and you should open bib 2, close valve 1, to clear it or help it. Just fiddle with it
and look for sound or visual changes. Give it some time to get things sorted out. Adjust the pressure to make the bubbles smaller if needed. You can even glance at it with a wary eye to let it know your watching. You might have to come up with some new words in the process, but it's only air, water, gravity, pressure, a few valves and a centrifugal pump. What could possibly go wrong?

Put a similar set of valves and tees on the other side of the X to fill and purge the heat exchanger side if needed (I'm not sure you do need them there).

Fill the tank. You can close valve 1, open valve 2 and let the auto fill purge the system by sending all air and water to the tank through the manifold and return line. Then the auto-vent you installed on top of the tank will vent the air. Meanwhile, your thermosyphon lines from the heat exchanger, that slope upwards, should let air trickle up to the tank and get out. In theory, you should be able to just fill it up and turn it on. The heat exchanger pump, if in the right place, may purge during the process and need no further help.

Now get that thing going so we can see how much energy it can transfer.

Install your expansion tank somewhere. It might be best on the top of the tank or on tee 1. You could put a second tee on the line running from your auto-fill to tee 1 and screw it on there. It also can be remote mounted but tied in at that point. That would put it on the suction side of the manifold pump which would tend to make the bubbles smaller in the manifold and make the pump deal with less air.

 

[Raspy]

You might be able to use the old burner control, as you mentioned. But be sure it is designed for line voltage on both outputs. Sometimes you can jumper the relay power supply terminals to power them with line voltage. From the factory, they might be set up to control a 24v circuit. Not sure why you need that control anyway as you cannot turn the heat exchanger pump off just because the room has gotten warm enough to turn off the thermostat. No room thermostat should be used here or you'll have run-away temps in the HX.

Your aquastat logic seem OK to me. Just be sure the bulbs are in the right places to sense the heat under any circumstances. I don't know why you need an additional controller. Just power the aquastats and they will turn on whenever there is heat. A simple wall switch that feeds them and provides a service disconnect should be fine. Since they are doing two separate jobs their run times will overlap but not start or stop at the same time. That's fine. I guess the only reason you even need two of them is to regulate the heat exchanger temperature more accurately and keep it hot to keep soot down. But I'm not sure that will make much difference. There is a lot to learn here.