in floor boiler

[swvega]

I just got a hydro smart 170 ng boiler for my in floor heat system. Hydro smart says to run two pumps. One to run boiler and one to run floor pexs.So you can run both systems at different speeds. This I understand but if the system is tee'd off to run the floor pexs and it's at a faster speed wont it speed up the other system too seeing as how it's all hooked together?

 

[aandpdan]

No.

The two systems run at different speeds. It really does behave as two separate loops.

 

[rlitman]

Look up "primary secondary loop", or "closely spaced tees".

 

[Highbeam]

seeing as how it's all hooked together?

You are correct, IF, you built your system that way. You can choose to either run an arrangement where there is one system of water being routed through the boiler and another system of water being routed through the floors. Two systems require two pumps. The boiler system dumps heat into the floor system by way of a heat exchanger.

The other and simpler way is to use a single pump to route water through the boiler and then through the floor. One system, the same water sees both boiler and floor. Only one pump is needed.

Your boiler manufacturer may, for some reason, require you to use the dual loop system aka primary/secondary.

 

[Jackfre]

Low loss header. Make it out of 3" copper with a supply and return to the boiler and on the opposite side a supply and return to the slab. This system duplicates the closely spaced tees, but gives a bit of margin for error and in my opinion is just easier. It is just a piece of open pipe with the four inlet/outlets and caps at both ends. Valve each separately. Support it well. Provide a bypass for flushing your system. You don't want the **** in the radiant tubing entering your boiler.

 

[BadgerBoilerMN]

I have been designing and installing hydronic radiant floor heating systems since 1987 and have never used a 3" manifold or fitting for that matter on anything short of a commercial snow melting system.

Always follow the manufacturer's recommendations unless you have the assistance of a qualified radiant floor designer.

Be careful out there.

 

[koditten]

I like the primary/secondary systems as well. It took me a while get my head around the concept. I finally looked at as the secondary loop "stealing heated water" from the primary loop. You don't want all the heat to be "stolen" just enough to get the input temps to the floor you are designing.

I actually put flow indicators on my primary and secondary loops. They are nothing more than propellers that spin acording to flow. They have sight glasses that let you see how fast the water is moving in each loop. The primary loop, the loop that comes out and into the boiler spins very fast. The secondary loop, the floor loop, moves at a very slow speed in comparison. In my opinion thise things should be manditory for hot water systems. You can see instantly if you have water circulating as it should be. You can also see the condition of the water as well. After you have varified that you have flow, you can start using your temperature gun to dial in you system.

As boiler mentioned, you should get assistance from the pro's. Doing the work is the fun part anyways.

 

[Bondo]

Low loss header. Make it out of 3" copper with a supply and return to the boiler and on the opposite side a supply and return to the slab. This system duplicates the closely spaced tees, but gives a bit of margin for error and in my opinion is just easier. It is just a piece of open pipe with the four inlet/outlets and caps at both ends. Valve each separately. Support it well. Provide a bypass for flushing your system. You don't want the **** in the radiant tubing entering your boiler.

Ayuh,... What yer describing is a Hyd. Separator...

I built 1 into a system I built last year for my rental house...
You can see it in the back corner, before the manifolds,...
Mine is 3" steel pipe,...

The primary loop, runs at 180°, 'n the tempering valve is after the separator, before the manifolds, which lowers the pex loop temps to 'bout 150°....

 

[Fastback]

I just went cheap, it works without issue and I would do it again. The only thing I would change is the number of loops in my shop, I needed one more to lower the delta without ending high temps into the floor, I am a bit more than a 20º delta-T when I send in 110º, but it seems to work well.

I cant imagine an electric boiler requiring a two pump system?