Lines in concrete

Brad White_94

entering or leaving a slab is protected by plastic sleeves, same at control or expansion joints. Obviously you do not want to enter or leave tight to a structural member where pinching occurs. Your tubing system manufacturer should be able to guide you and provide the appropriate parts.

The coefficients of expansion are similar enough that the movement between the two materials should not be an issue.

Your manifold should be closer to the demand in my opinion. Often the total circuit length omits that final home-run.

Where the pump goes depends on several things. If all circuits ("zones" by your definition?) use the same temperature AND so does the rest of the house, then the boiler would dictate the overall temperature and this give you more location flexibility. (I am assuming here that you have no higher temperature zones such as radiant panels or air handlers.) Just insulate the piping well, especially of the lengths are on the long side.

If the radiant slab is of a different perhaps lower temperature your circulator for that temperature should be at the manifold where the mixing would occur. And as stated, the manifold should be held close to the load.

Hope this helps.

Brad

Joe_75

Lines in concrete

I have two questions about my heating system that I am installing in my home. I have an accurate heat loss and have most of the materials that I was told I needed.

How do you get the lines from a floating concrete garage slab into the crawl space without worring about them getting pinched because of slab movement?

With six zones what is the best way to tie into the primary loop. Do you run a line from the primary to your manifold that could be 50' away and if so where does the zone pump go. At the primary loop or at the manifold.

Wayco Wayne_2

Protect

your tubing with PVC sleeves where approprite. What is your hot water source? If you have a boiler you might want to repipe it in a primary/secondary configuration. That way you could run some mini tube lines off a variable speed injection circulator to a manifold station that has it's own system circulator for circulation through the radiant zone. Tek mar variable speed controls are what I most commonly use for this although there are other control companys that have it to. WW

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hr

Why a floating garage slab?

How much movement are you planning on? Seems most slabs around here are rebar pined to the footer or foundation walls to prevent movement.

Are you building on permafrost?

hot rod

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Joe_75

No I was just worried about possible movement because the piping for the slab will have to go directly through the crawl space wall or through the rim joist. The problme with the rim joist is that it is a foot higher than the slab.

Joe_75

I do not think that I was to clear on the question. The zones/circuits are of differnet temps. I have supply and return maniforls for each zone. The primary loop runs constant with a plate heat exchanger from a outdoor wood boiler and there is also an electric boiler on the primary loop for back up. The system needs a max of 16GPM at -20. What I was wondering is should I run a sendary loop to feed the zones or should I run off of the primary loop.

Brad White_9

It all depends....

I see no reason not to run your primary loop around and branch off to each. But without seeing the building one cannot say for certain.

If your mixing occurs at each manifold, I figure the "local" zone flow is taken care of so your primary flow only has to make a round-trip near them.

To determine the best way for you, you should figure on doing a cost-benefit analysis.

For example you may have a 300 LF run of 1.5 inch piping for all I know. The cost for this will be x. (More like X!)

If you run branches out to each (micro-tubes in 3/4" copper or PEX-AL-PEX) the costs may be significantly less depending on distances.

Sketch it out on paper and see which is most cost effective for the actual layout.

Personally I favor less pumping which is why I favor primary flow. Running high temperatures as you would from wood, you have a good mix to primary ratio which means small tube sizes.

Joe_75

Brad,

Thanks for the reply, I will try that and see.