Radiant Heating - loss of heat within the same zone

phillycheese

Hi all, a newbie here.

I recently realized one of my four zones is not heating up well (radiant heating). When I followed the pipe/water flow, it becomes less and less warm as it goes on. Maybe it's nothing too strange but the degree of heat loss is unusual, different from other zones. Toward the end of the circulation, in the bathroom, there is almost no heat at all.

Any idea what could be causing this? This zone is dining room and kitchen area, not particularly exposed to external chill.

Many thanks in advance.
Philly in New England

hot_rod

Is it a much longer loop than the others in the zone? Do you have a way to measure temperature at the beginning and end of the loop?
Is there a flow meter anywhere in the loop, at the manifold?
It takes temperature and flow to move the heat energy.

bburd

Sounds like insufficient flow, which may have a number of causes.

phillycheese

Thank you both for the comments.

@hot_rod I don't think it's much longer than the other zones. The beginning of the pipe (first baseboard) is too hot to even touch yet the ending is just cold, again in the bathroom. We don't have a flow meter.

@bburd Just so you know, I manually opened the valve (Taco) fully to see if it was the issue but it didn't get much better. Still cold toward the end of the loop. 

hot_rod

Copper tube baseboard or radiant heat with Pex loops?

phillycheese

Thanks for the comment, it's cooper tube baseboard(s).

hot_rod

Any valves or strainers/ filters in that loop?
Has it ever heated properly?
If it is a very long loop you could expect 30 or more degrees of temperature drop under load conditions 

You could close down the dampers on the first few baseboard to get more temperature at the end of the loop. Bump the boiler temperature up a bit.

An inexpensive strap on thermometer would tell more of the story. Check temperature at both ends at first start, and every 10 minutes or so