Baseboard Heater Issue

[hj]

That venturi tee does two things. First it creates some resistance, which forces water to be diverted into the line going to the radiator. Second, and maybe most important, is that the water flowing through the venturi creates a pressure DROP after the tee which helps pull the water through the radiator. BUT, the venturi effect depends on a certain water velocity, as does the amount of resistance through the tee. If the pump does not deliver that flow, then the venturi does not operate, and very little flow will occur through the radiator.

 

[Spta97]

So the pipe isn't cast iron it's black pipe/steel.

As far as corrosion the fact the boiler is a closed system there isn't new oxygen being introduced to the system. Therefore corrosion is most likely limited to what you see on the outside.

In my 100yr old house there wasn't any corrossion other than surface rust which is to be expected on black pipe that is exposed.

Thanks for the correction - I was not aware of that.

I have had to drain the system several times when doing other plumbing work but I do bleed out each of the heaters every season so hopefully I didn't introduce oxygen to the point of corrosion.

 

[Sponsor]

 

[Spta97]

First off that is a B&G venturi Tee and it is properly installed. The venturi tee works on a reduced pressure principal in that an area of low pressure is created at the ventrui that pulls the water through the convector, and those are convectors, not baseboards. There is a slim chance that the convector is plugged but I doubt that is the issue. More likely is that the venturi inlet ( to the convector ) has some crap in it. You could try back purging the loop or cut the copper right at the tee and run a wire down to clear it out.

Peter - thanks. How would I go about "back purging" without introducing the contaminats into other areas of the system? This heater that does not work is in my office and I typically have two monitors on at the same time (laptop and computer) so if there was a room that I can deal without much heat this is it....I would hate for this to cause one of the bedrooms to go out.

Thanks for the correct name too - convector! We used to have a really good guy in the plumbing isle at Home Depot who told me that but I had forgotten the name. He informed me that they generate more heat than baseboards and typically when replacing with a baseboard I would want to multiply the length times 3 to get the same heat output. In the rooms that I have done that it seems to work fine.

 

[Spta97]

That venturi tee does two things. First it creates some resistance, which forces water to be diverted into the line going to the radiator. Second, and maybe most important, is that the water flowing through the venturi creates a pressure DROP after the tee which helps pull the water through the radiator. BUT, the venturi effect depends on a certain water velocity, as does the amount of resistance through the tee. If the pump does not deliver that flow, then the venturi does not operate, and very little flow will occur through the radiator.

hj - The pump is making noise and there seems to be water flow to the others ( I got a good spray when taking off the old valves before I realized I had to drain

I wonder, if it was a pressure problem would it only show up at the last one or would it be a problem with all? As mentioned, the others seem to be generating sufficent heat.

 

[Jadnashua]

A typical hot water residential heating system is pressurized to about 15psi, give or take a bit. If the house is multistory, it might have more. Any time you drain and then add water to a system, you are introducing oxygen. As long as you don't have a leak, and it happens on an on-going basis, it shouldn't be a problem. If the circulator can produce enough head, and there aren't huge differences in flow resistance between branches, you should get flow but it may not be even. Sometimes, yohu need a way to balance the flow between branches. Sometimes they'll do that by just putting another pump for each branch.