Disappearing Water in Closed Loop System

JimmyZ

My first time posting here, and I'm not a heating contractor, just a simple homeowner, but am looking for some answers or recommendations.  Our home has an in-floor heating system that is hot water driven in a closed loop.  Last year, the water in the system ran low, so a contractor came out and refilled the system somewhat by connecting the drain outlet from the hot water heater that feeds the house water to the drain outlet from hot water heater that feeds the system (they are identical heaters, side by side in the basement.)  Both of these water/drain outlets are at the bottom of each tank of course. He needed to fill it this way since the in-floor loop system has no way of filling it.  Obviously, by filling it this way, there was no way to completely fill the tank again since it only filled as much as the pressure in the twin tank pushed water into the system tank (got that??)  This seemed to work since the pressure gauge came back up to maybe 15psi and we had heat the rest of the winter.



Now, this fall, when we tried to use that in-floor heating again, the tank appears to be low and in generating no pressure.  I tried the contractor's same trick by hooking up a hose between the two heaters, and I could tell it put quite a bit of water into the in-floor system water heater tank, but I am still not getting any pressure reading on the gauge. 



I guess if there is air somewhere now in the system, the way that this system is designed, there is really no way to let that air out now ..... would that be affecting the pressure?  On the top pipe on the system (see the picture) there is a "Spirovent microbubble absorber" that appears to maybe been a way to let air out ... but it looks like the end of it is fused shut ... is/was that an air escape valve of some sort? Would you recommend having someone open that valve up? Also would you recommend that a water source be hooked up to the system near the top like on the household water system so that we have an easier way to add water when the system runs low?  Finally, is evaporation like this common in a closed system, and if so, why would someone install a system like this without a way to add more water to it?



Any help you can provide would be greatly appreciated!



Jim

lchmb

Do

yourself a favor and click on the "find a contractor" link on top of the page. Get someone in who is familiar with hydronic's to get you up and running properly...

Gordy

More pics

Take a few steps back, and take more pics of your system.  It could be a lot of things. Some simple, and some may be complicated.

JimmyZ

more photos

Here are a few more photos of the system in case that helps ... thanks!

Gordy

Some thoughts

Expansion tank pressure needs to be checked when isolated the from system. It should be 12 psi. use tire pressure gauge. It may need replacing.



You said that the system was filled from the domestic water heater. The Radiant system should always be filled at ambient temperature to the proper psi. Using hot water from the water heater will give a false psi reading of what it should be.



  Hot water will give you a higher psi reading from when the system is at ambient. So if you filled to 12 psi hot it may only read 6 psi when ambient.



 Hot water takes more space in the system than cold. If the x tank has failed you would probably have a weeping pressure relief valve on the water heater because the tank cushion is not allowing for expansion. I see it may have been changed from the pic there is one laying on the water heater.



 It is possible you have a leak somewhere. But you need to make sure the above things are correct, and move on from there if there are not any noticed leaks.



Is this radiant in a concrete slab?



Gordy

JimmyZ

Reply

Gordy, thanks for the feedback!  This is indeed a system in a cement slab basement floor.

Gordy

Manifold Pic

If you could please Jim. You could easily T in a cold water feed with a pressure reducing valve so you do not have to fill from the water heater also. T in above the X tank. Also install a shut off valve above the X tank so it can be isolated and replaced easily.

JimmyZ

Manifold Pic

I'm sorry, not to be an idiot, but what part is the manifold?

Gordy

Manifold

Is where the tubing in the floor converges in the system piping. I think there is a glimps of it with orange tubing in one pic.



Gordy

Jean-David Beyer

It seems to me that there are two manifolds in a hydronic system

At least, if there is one, there must be two.



But you will have a tough time finding one of them in my house. The one on the supply side is a bunch of Ts with ball valves. One-inch enters a tree of Ts, and 1/2 inch leaves and disappears into the concrete slab. You will never find the other one unless you have a thermal imaging camera, because it is a bunch of Ts buried in the concrete from which a one-inch copper tube exits.

JimmyZ

Manifold Pic

Here is a photo of the manifold

Paul Pollets

Leaks in tubing

You have an early Levitt system that uses copper tubing embedded in the concrete slab. There may be a leak causing the problems you describe, as these systems typically have a 50 year life expectancy. The copper tubing within the slab gets corroded from the concrete alkalyds and pinholes develop. Installing a pressure gauge on the system and charging to 50PSI should indicate if the tubing still holds pressure. Make sure the water heater is isolated before pressure testing.

Jean-David Beyer

Leaking in slab?

I have a house with a 61 year old concrete slab with copper tubing in it. If mine leaks, it must be that the brand new indirect hot water leaks at the same rate into the system. I turn off the makeup system from time to time, for over a month and the pressure does not go down. I infer no leaks. I would leave the makeup off all the time, but my service company has a fit when they see it off. I do have an M&M probe type low water detector that powers off the entire system if it feels thirsty. When the makeup is shut off, I look at the pressure every day just to make sure. The gauge may not be accurate, but it is precise. If the circulator to the indirect runs, the pressure drops a little due to loss through the heat exchanger, and it returns to normal when the indirect is satisfied. I have toyed with putting a 3" or 4" pressure gauge on the system, but I have not done so. I also thought of adding a cute little water meter, but I have not done that either..



http://www.jerman.com/dljmeter.html



The OP said something to the effect he could not he could not raise any pressure on the gauge. That would be an extremely bad leak, it seems to me, one that would make a big mess of water all over near the leak. Unless his house is built on sand, and the water leaking out under the slab, I would think the location of the leak would be really obvious.

Gordy

Levittown

 Paul I thought most of those homes were slab on grade, or are you just refering to copper in concrete a (levitt system). This appears to be a basement from the pics.

To OP is that tubing going into the concrete plastic or copper? Color seems a little off to be old copper tubing.



JDB a lot of it is the make up of the concrete used, and the soils of the location. High flyash content can be aggressive to copper. Cinders also.

Jean-David Beyer

Makeup of concrete in slab?

"JDB a lot of it is the make up of the concrete used, and the soils of

the location. High flyash content can be aggressive to copper. Cinders

also."



I am sure you are right. I wish I knew more about my slab. In particular, I do not know:



1.) the layout and spacing of the tubing in there. I have guessed, but the guess that best reflects what the balancing valves do is stupid.



2.) How long this 61 year old slab will last; part of this is surely the flyash content. If I live to be 100, I have 27 years to go. I guess if it leaks, I will have to balance just adding makeup water and shortening the life of the boiler, getting out the jackhammers and fixing the leak (probably a terrible idea because if there is one leak, there would probably a lot more to follow), or putting radiant in the ceiling. No room for baseboard, and it would probably need higher temperatures.



3.) Whether there is any insulation underneath it. My guess is that there is not, but perhaps I am fortunate that the water table is at least 6 feet down.



3a.) If there is perimeter insulation around it. My guess is that there is not. Within 12 to 24 hours, snow has melted over a foot away from the building.



A question about #2. If I can heat this house just fine with my radiant slab, does that mean I have enough ceiling area to heat it with radiant ceiling? I guess so, but is there a gotcha hiding in there somewhere?

Gordy

JDB

 I would not panic I have radiant in concrete that old also, so far its fine. Yes ceiling radiant is an option if need be, and its quite comfortable. You would definitely have enough ceiling area to compensate for the floor area barring any cathedral type ceilings, expansive sofits etc. If you think about it RFH has furniture, floor coverings, cabinetry etc either blocking output, or decreasing available radiant area to heat the space.



 Chances are if your tubing has lasted this long then there was not an aggressive concrete mix used, or soils, and water.



To answer question a little time, and an infrared thermometer you could replicate the tube layout.



As for inulation I doubt it fuel was cheap back then. Some times they would keep the tubing away from the perimeter of the slab 24-30" as a buffer zone. thats what they did in my basement.



Gordy

lchmb

a concern

In the first set of pics it appears that he is still using the xl100 prv for the system. 

JimmyZ

Age of my system

The in floor heating system I have is indeed in the basement, though the home is built into the side of a hill, so it is a walkout.  Also, the home is less than ten years old, so the install of the in-floor heating system would be from the same time.  Finally, the guy that built this house fashioned himself a contractor, and at best, it would appear he was inconsistent as a contractor, since some things he did in this house were top notch, and other things somewhat inexplicable, like perhaps this in-floor heating system.  The stuff he hired out was done right .... the stuff he did himself, not so much.  The couple of water guys I've had over at the house have mentioned that the hot water heaters he chose for both the system and the floor are not the best brand or quality .... for what that is worth.  Thanks for all the help so far!



Jim