Radiant manifold question.

[RK-REX]

I've been tossing around ideas for the manifold for my new hydronic set up. I've got 6 circuits to plumb and with the price of a good adjustable manifold, I thought I'd just make my own as some of you have. I've found that the major cost in a purchased manifold are the flowmeters. I can get them through one of the suppliers I deal with, but even with a discount, they're still around $50-$60 a pop. So here's my thought, tell me what you all think.

I'll make up a manifold with copper pipe and use ball valves for flow adjustment, just as some of you have. Then rather then a flow meter, I will buy temperature labels and attach them to the return lines so I can monitor the return temp of each circuit. They are accurate within +/- a degree or so. This should give me an accurate representation of where I'll need more flow to maintain the circuit temp. and thus the floor temp. I will start with all of the valves flowing at around 75% and adjust to get them all the same temp on the return side.

It's been a long time since I've had a physics class, but does this sound like it will work or should I lay off the Guinness at lunch?

 

[RK-REX]

35 views and no answers, suggestions or no way comments? Does it at least sound logical to anyone else but me?

 

[PAToyota]

You're basically saying that you will monitor the return temperature and adjust the flow manually?

Shouldn't be a problem unless certain circuits vary over time for whatever reason - say the circuit by the garage doors cools off faster than other areas when the temperature drops at night.

In the long run, you're talking less than $400 for flowmeters in a build costing thousands of dollars? I'd just go with the flowmeters, be done with it, and not have to think about it again.

 

[RK-REX]

You are right. I'm just the type to think this way and not look at it in the same light you did. It just seems that everytime I turn around it's another $3-400 or so. Well, that and the wife is threatening to start Ebaying my motorcycles if I spend much more. LOL

 

[mike944]

Ok, i'll admit i was one of the 35 views. I don't know enough about radiant heat systems to answer your question. So, in the interest of learning something, i've got a question.

What exactly do the flowmeters do? I assume they measure flow, but how are they used? Is there a flow adjustment knob for each loop, and you set all loops to flow the same. In other words, set it once, and never touch it again? Or is it some kind of automatic thing that continuiously adjusts the flow based on return temperature? or based on something else.

 

[PAToyota]

I can understand getting to the point where - as you say - it seems like the money just keeps flowing out of your pocket in a continuous stream. But it is also like the people that buy a new car every few years because they don't want to face all those repair bills... Ummm? Ok? So you want to pay $350 every month for the next four years on a new car to save paying $500 once a year on repairs?

I guess my two questions with the temp gauge/ball valve setup are:

• whether you would get fine enough control with the ball valve or whether it would go too far one way and then the other
• as stated before, would certain zones fluctuate more than others and lead to constant fiddling with things

From there, decide whether it is going to be worth more to pay up front and eliminate future frustration or whether it isn't going to be much hassle and will save you a few bucks.

 

[5wndwcpe]

This is essentially what I had planned to do with my system. I was going to use a IR gun instead of the temp. labels but it's still the same principle. What is important is the temp differential, not the flow rate. Yes, I know they are linked, but who really cares what the meters show. If you're going to use the return side temperature (via thermal gun, gauges, tape etc.) to balance the system anyway, why pay for flowmeters. One thing you might consider is adding mini ball valves to the supply and return side of the manifold(s). My thoughts on this were it would make purging the system easier, draining the system should it be necessary and isolating a loop should (God forbid) you drill into the tubing by accident.