Radiant Heat

[Danh123]

Hello,

I purchased a house with an in floor water pipe radiant heat system with a buderus boiler and controller. I am looking to gain a deeper understanding of how the system works. Two of the actuators look old and I am planning to replace. When I take the actuator off and see the pin sticking up from the manifold, how can I test to make sure that part is working? I press down with a screwdriver and it goes down. Should I hear the sound of water when I do this?

Also, when I went down to look at things today, two of the actuator heads were popped up. It was a cooler day in the 60s and rainy. The controller was set to 64 and the room temperature was 70. I'm not sure why the system was on. There is the one controller in the living room that sets the temperature and there are 4 thermostats throughout the house that open or close the zone based on their temperature. I went and turned all those down to 60 and went as low as the controller would go and the actuator heads went back down. Why was the system running?

I uploaded a couple of pictures.

 

[Jadnashua]

Normally, there's very little, if any, flow noise with a radiant system, so IMHO, it is not uncommon to not hear anything when you open the valve. The circulation pump may not have been on, either, as it would not be activated by you pressing the valve open. The only time you tend to hear water flow in these is if there's some trapped air that hasn't been purged.

Radiant heat tends to work best when it is run without a setback, since for maximum comfort, it is generally sized close to the design needs...IOW, there may not be a huge amount of radiation excess available to recover from a setback, but has enough to keep up, once there, except on a mild day.

Are the sensors for the thermostats in the floor, or up on the wall? If they're on the floor, especially if the a/c is running, the cool air tends to pool there, and it could have been below the set point, turning the system on. If they're actually up on the wall, they probably shouldn't have been on.

 

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[Dana]

A better description of the zone controller and thermostats, as well as the floor radiation might provide more insight. If the floor is a concrete (structural slab, or lightweight "gypcrete") there are time lag issues that can cause temperature overshoots. The overshoots, particularly the magnitude of overshoots on the higher thermal mass radiation can be pretty big during light loads followed by no-load, such as a chilly morning on a day when it's 70F and sunny by noon. Smarter thermostats can sometimes compensate for that.

Zone valves can be pretty cruddy/dirty/old looking and still work just fine for decades- don't let mere appearances drive a decision toward replacing them.