Infloor heating too high

jamespet

I am having an issue with my radiant heating. The temps in the lines were about 160F. I had a company come over and they installed a mixing valve. However when only one zone is being called the temps still rise over 160, but if there are more zones then the temps seem to be about right. I had the company come back out to look and they said it was correct. I am still not sure. I created a drawing of how my system looks at the moment. Any thoughts would be appreciated.

GroundUp

Can you show us an actual picture of your actual system? How many loops per zone? What kind of mixing valve? Is the system circ pulling away from the mixing valve?

hot_rod

Your boiler circ and mix valve circ are in parallel 

Does the floor get flow when its circ is off?
Is there a check valve in the indirect circ?
primary secondary piping would be better

mattmia2

hot_rod said:

Your boiler circ and mix valve circ are in parallel 

Does the floor get flow when its circ is off?
Is there a check valve in the indirect circ?
primary secondary piping would be better

I think they tried but their closely spaced tees aren't.

jamespet

GroundUp said:

Can you show us an actual picture of your actual system? How many loops per zone? What kind of mixing valve? Is the system circ pulling away from the mixing valve?

hot_rod said:

Your boiler circ and mix valve circ are in parallel 

Does the floor get flow when its circ is off?
Is there a check valve in the indirect circ?
primary secondary piping would be better

mattmia2 said:

hot_rod said:

Your boiler circ and mix valve circ are in parallel 

Does the floor get flow when its circ is off?
Is there a check valve in the indirect circ?
primary secondary piping would be better

I think they tried but their closely spaced tees aren't.

Not really sure what most of that means. Here are some pic of the actual system.

EdTheHeaterMan

Not really sure what most of that means. Here are some pic of the actual system.

No Hydraulic separation when the pumps are parallel. Two pumps doing the same thing. Makes for more energy pushing the heated water into pipes that you may not want the water to go to. (see the black arrows) on the Current Setup. The Better Setup shows how primary / secondary places each pump in its own loop separating the loops so the pumps are not parallel. Boiler Loop (Red arrows) with the boiler circulator. The DHW loop (Green arrows) and the radiant floor system loop(s) (Blue arrows) with the system circulator. Each circulator can operate without effecting the other loops for better temperature control.


By using the Closely spaced tees (that is called primary secondary piping) to hydraulically separate the pumps, (see the shaded green and blue) the mixing valve can do the proper job with only one or 2 zone valves open. When there are 2 pumps pushing the water from the boiler to the radiant floor, sometimes the mixing valve might get pushed open by the extra pumping energy and add more heat than the floor actually needs.

How old is the system? Can you get the installer back to pipe it properly? They will learn something from their mistake and we will be glad to assist in their education. Just guide them on HeatingHelp.com. Free education for the price of doing it right the second time. Not a bad deal!

Mr. Ed

jamespet

I think about 15 years old. I don't know if I can get the original installer. He was the original owner and long gone.  I could get the company that installed the valve, but I need to provide this information in a way that does not aggravate them.  Like I said, I had them back out and they assured me it was correct.  

I understand the primary loop.  I even mentioned that to the technician that came out.  But I am not sure I understand the closely spaced tees and the water flow at them.  

mattmia2

The closely spaced tees make it so that the flow from the circulators in each loop don't interact with each other. They provide hydraulic separation.

Maybe avoid bringing the company that burned the plywood instead of pointing the torch away from it back.

Was that valve off to the right a fixed bypass that regulated the radiant temp?

HomerJSmith

Your pump is mounted vertically which is incorrect. It should be mounted horizontally.
The problem I think is with the mixing valve; There has to be a temperature differential between the hot and cold inlets for it to work properly. The radiant loop pump should be a ECM pump if you have thermo-actuators on a manifold and the loops should be balanced. As stated check valves and separation between the tank and radiant circuits is how a properly piped sys should work. That would prevent one pump from interfering with another pump.
Ed Young's diagram as to piping is very good.

mattmia2

Did this work properly at some point?

jamespet

mattmia2 said:

The closely spaced tees make it so that the flow from the circulators in each loop don't interact with each other. They provide hydraulic separation.

Maybe avoid bringing the company that burned the plywood instead of pointing the torch away from it back.

Was that valve off to the right a fixed bypass that regulated the radiant temp?

I the tech explained it was something like that. It is just cracked open to allow just enough water to recirculate.

jamespet

mattmia2 said:

Did this work properly at some point?

Not since we moved in.

jamespet

What is this? It was removed during the process of the adding the mixer valve and a manual ball valve was added. See the diagram of the bypass near the radiant heating? Is this some kind of pressure release valve that should have been left on?

mattmia2

it is a pressure bypass, it should have remained. It serves the same function as the ECM circulator that someone recommended.

jamespet

mattmia2 said:

it is a pressure bypass, it should have remained. It serves the same function as the ECM circulator that someone recommended.

OMG. gunna have to have them fix everything.

HomerJSmith

Just follow Ed Young's diagram. You will have circuit separation between pumps. If you are zoning with zone valves add back the pressure bypass valve and set it properly or convert to an ECM pump and forget the pressure bypass valve.

I would also think about a sensor mixing valve and not the proportional thermostatic mixing valve you have now. Bad mounting, not horizontal.

HomerJSmith

HomerJSmith

The cold inlet and hot inlet show the same temp. That mixing valve might not be regulating at all when one zone is operating.


When all the circuits are operating the cold return to the mixing valve would be cooler and have a greater temp differential between hot and cold.

jamespet

HomerJSmith said:

The cold inlet and hot inlet show the same temp. That mixing valve might not be regulating at all.


When all the circuits are operating the cold return to the mixing valve would be cooler and have a greater temp differential between hot and cold.

In that pic, I think everything was idle for a while. the temps are about 70-80 so its been sitting.

HomerJSmith

By the way in Ed Young's diagram don't forget the needed check valves.

Dave Carpentier

Might be worth having a different company come out and at least looksee.
If they start talking along the same line as the pros here, then you know you've found your local tech support.

EdTheHeaterMan

A lot has happened since I last looked at this. For the answer to @jamespet query on the purpose of the closely spaced tees. There is an easy explanation that is better seen than described in text version. When any circulator pump is operating there is a higher pressure on the discharge side of the pump and a lower pressure on the inlet side of the pump. as the water moves thru the closed piping system the friction of the water moving past the pipes and fittings reduces the pressure incrementally thru the system. In order to get the Hydraulic separation provided by a primary secondary design, the closely separated tees are essential.


If you can zoom in on the primary circuit on the left, there are gauges places all around the loop. The closed system boiler pressure on the discharge side of the operating pump is 15 PSI. This makes the inlet side of the pump have the lower pressure of 8 PSI. If you were to place a pressure gauge as several locations around the primary loop you would see how the friction loss of the water moving past each length of pipe and each fitting will cause the pressure to drop gradually across the primary loop. If you were to read the pressure at the supply tee branch pipe of the water heater loop you might see 11.5 PSI. As you travel around the primary loop to the tee branch of the return of the water heater loop the pressure would read close to 8 PSI. As a result of the pressure difference in the supply and return pipes of the water heater loop, you would expect some flow to happen thru the water heater circuit whenever the primary loop pump (Boiler pump) operated. Even without a pump on the water heater loop.

In the diagram on the right when the water heater loop is connected to closely spaced tees, the pressure difference between the supply and the return of the water heater loop is so low that no water will flow to the water heater loop when the primary (Boiler) circulator is operated.

This is the hydraulic separation that the closely spaced tees provide in Primary/Secondary piping design.

I hope this helps @jamespet see the water moving inside the pipes in his minds eye.

Mr. Ed

Disclaimer: The pressure readings are for illustration purpose only and may not be actual pressures of any particular system. The pressures on your actual system will vary based on Pump selection, pipe size and number of fittings. In other words, don't nit pick on the numbers, just understand the concept.

Oh yea, I almost forgot to say "The names have been changed to protect the innocent."

EdTheHeaterMan

As far as getting the original installer back to fix his mistake, I was under the assumption that the system was less than a year old and you may get the repairs completed for free. Since the system is 15 years oldish, then the statute of limitations on poor quality design has long since passed. It probably never worked right but someone should have mentioned it much sooner. You need to find a competent boiler guy/gal/other to get your piping correctly designed.

(don't want to exclude anyone)

Mad Dog_2

Great Explanation Eddie.  You should teach.  Mad Dog 🐕 

jamespet

EdTheHeaterMan said:

I hope this helps @jamespet see the water moving inside the pipes in his minds eye.

Wow. Yes. awesome information.

On a side note. I just had the company out to take another look. I had sent them the diagram that you had put together. They finally believed me that the piping was incorrect and needed adjustment. It was explained in order to accomplish what was in the picture that I would need quite a bit of work done. I don't really see it that way, but they went through a list of things that were needed and costs started to get high (on top of what was already done). 4kish additional work.

IDK maybe this is correct. I asked if for now could we just get the primary loop working again. I don't remember, but it was somewhat mentioned that they could just put back what they did or do a full update. My boiler is old. I will probably replace it in a few years any way. It will need to be redone then anyway.

Should I really bother now if I'm just going to have to redo things then anyway?



I suggested a fix for now and they would not do it. Is this not acceptable to get the primary working again. I included very clumsy photoshop and a pic from another perspective to maybe see it better. I color coded the same as the original. Wouldn't this get it flowing correctly again?

mattmia2

That boiler could last another 20 or 30 years or more. They are trying to sell you a boiler. It won't fix your problem.

This looks like it was done by someone who knew what they were doing so presumably before something broke and then it was monkeyed with by the incompetent it worked, so you need to figure out what broke. If it was done by the previous homeowner and they got something wrong they would have fixed it.