system design?

Andy_14

Can anyone help with putting together an in slab system for me. I have found so many differing opinions I don't know what is right or wrong.

S Ebels

Details

Do you have any components or equipment bought yet? How big is the slab? Are you planning on insulating underneath?
What fuel are you using? Do you know what the heat loss of the building is?

These are just some basics to get started with. The a dozens of other ??? and variable factors that have to be dealt with. I'll be happy to help as much as I can and I'm sure others here will chime in too.

Andy_14

> Do you have any components or equipment bought yet? No...

> How big is the slab? Slab area that can accept pex is 1600sq ft, but whole area is 2400sq ft...
> Are you planning on insulating underneath? Yes, 2" ridgid foam board..
> What fuel are you using? Natural Gas...

> Do you know what the heat loss of the building is? I have gotten differing answers on this. So I would have to say no...

>

> These are just some basics to get started

> with. The a dozens of other ??? and variable

> factors that have to be dealt with. I'll be happy

> to help as much as I can and I'm sure others here

> will chime in too.



Thanks very much for your help.

Andy_14

From reading posts here, it sounds like I need to get an accurate heat loss calc. first. But I think it's around 85,000 btu's/hr.
The Trinity T-150 is in my price range and sounds like a decent unit. Anyone have opinions on this boiler for my application.

Constantin

Second the heat loss calcuation...

... if it's a concrete slab, figure on about 1' of PEX per sq foot of area. Run the PEX on 6" centers near exterior walls, then go to 12" OC on the inside. Buy, and read Dans book on the subject. Then read Siegenthalers Modern Hydronics book also. That should answer most Radiant heat questions.

Most importantly though, get your client interested in proper insulation. What you have indicated so far sounds like a lot of heatloss for such a small area. The Building Science Corporation has excellent online and printed builders advice re: proper construction techniques. Then check out the Energystar Building program to get someone to audit the place and pay you guys a rebate if it passes muster.

Constantin

Oops...

double-post, sorry.

Andy_14

This is new construction, 2x6x16' walls R-19, ceiling r-38. Approximately 400sq ft of glass in the building.

John Starcher_4

Andy....

...the Trinity is an excellent boiler for this application. I have one in my shop feeding three zones of radiant, and it works wonderfully.

CRITICAL: You must follow the installation instructions carefully, and maintain proper flow through the boiler. It is easy to do if you size your piping and circulators properly.

Starch

Andy_14

> CRITICAL: You must follow the

> installation instructions carefully, and maintain

> proper flow through the boiler. It is easy to do

> if you size your piping and circulators

> properly.

>

> Starch



I don't really understand how this works. Can the circulator in the boiler be adjusted to flow at different gpm? I will be doing 1 zone (one room approximately 2350sq ft.)

Pinball

There is no circ "in the boiler" what you need is a primary secondary system.The primary loop circ. must be a taco 010 or eqivalent. The secondary circ must be sized to the load. Also the boiler is stubbed out with 3/4 inch pipe. you must increase the primary loop to 1-1/4 as soon as possible, after the gauge and relief valve setup.(explained in manual) In addition, be sure to follow the venting instructions carfully as well. These are great little boilers, and bang-for-your-buck will work perfectly in your situation.