RADIANT FLOOR HEAT

Jack_9

I purchased a system from an Internet heating co. ,and should work just fine, however the system they recommend is called an "OPEN DIRECT SYSTEM' which I am not to keen on, it uses DHW to heat the the floor. Here is my question, I have a gas water heater which would put out enough BTUs to handle this open direct system. but, I originally planned on installing baseboard heat and purchased a sentry boiler which can also handle both DHW and radiant floor heat. I am not to familiar with what controls, heat exchangers, and indirect water heaters would be best suited for my application.

My specs are as follows:
Boiler: slant fin sentry S-90 Net BTU=66K
Water heater 40 gal 35K BTU
Home:1440sf. superinsulated total est. BTUs/HR.:25K
Tubing: 7/8 pex, 1080lf BTU output 43K, gals of water in floor 29gal
1 floor, 1 zone 2 adults 2 children

Mark Eatherton1

Use caution here...

The internet companies I'm aware of are selling a non oxygen barrier tubing which can not be used with ferrous components in the system. In order to use the tube you will have to either use a heat exchanger to isolate the ferrous components from the oxygen permeating tube, or use all non ferrous components.

THe BTUH output per linear foot looks wrong. Output depends on a lot more than just diamter and length. Did they ask you what kind of floor covering you planned on using? Did they actually perform a heat loss calculation for you? If not, they're in direct violation of the Internationa Mechanical Code.

Off hand, which company are you dealing with?

Its really not as simple as they make it out to be...And if you do it as they say, using the DHW heater as a combination water heater/space heater you are exposing yourself and your family to potential water bourne bacteria including Legionella. Did they mention anything about that?


ME

Jack_9

Proceeding with caution...

I am aware that the tubing does not have an o2 barrier so I would have to use s.s. . The operating temp. is between 120-135 deg. Yes they did ask about flooring 3/4 in. subfloor & 3/4 in. strip floor. A heat loss calc. was done, the company is the radiant floor co. thanks for the response

Mark Hunt

Reconsider sir.


You will be buying an orphan system.

Once the Inet company gets your money you are on your own.

Open systems are a trial lawyers dream come true.

There is so much more to this.

Mark H

To Learn More About This Contractor, Click Here to Visit Their Ad in "Find A Contractor"

Jack_9

If my home uses hot water on a daily basis i.e.: showers 4 people, dishwasher, laundry, and sinks, my water heater holds 40 gals & 29 gals in the system its still under 75 gals. I don't think the water would stay in the system long enough to stagnate.

eleft(retired)_3

\"stay in the system long enough to stagnate\"?

Jack,

First, the contest you are trying to engage has no prize. Second, what is the water doing in the tubing on the radiant heating side of your proposed system when there is no call for heat (think) and, when the call for heat does come? Last, you are getting professional knowledge free from the most experienced people in this business... so you now know.

KNOWING AND NOT DOING IS NOT KNOWING.

Why put your family at risk?

al

Jack_9

In my original posting I said that I wasn't too keen on this type of system. However, the responses I got did not address my question, I am aware that I am getting free advice from some of the best minds in the industry. Although I am not an HVAC tech or Plumbing contractor I like to tackle most projects myself. I have been in the construction industry over 20 years and built this house from scratch with much success including the plumbing. The problem with hiring a contractor here in upstate New York is if they're any good I won't see them till April, all that's left are the barflies and it's going into November, So maybe I should have just installed the baseboard heat I originally planned on. In any event I need HELP, Thanks,
Jack

Mike T., Swampeast MO

Jack,

> In my original posting I said that I wasn't too

> keen on this type of system. However, the

> responses I got did not address my question, I am

> aware that I am getting free advice from some of

> the best minds in the industry. Although I am not

> an HVAC tech or Plumbing contractor I like to

> tackle most projects myself. I have been in the

> construction industry over 20 years and built

> this house from scratch with much success

> including the plumbing. The problem with hiring a

> contractor here in upstate New York is if they're

> any good I won't see them till April, all that's

> left are the barflies and it's going into

> November, So maybe I should have just installed

> the baseboard heat I originally planned on. In

> any event I need HELP, Thanks, Jack

DaveGateway

I'm confused. You have the boiler, so why not use it?
Use a heat exchanger to eliminate the non O2 problem.

I can't understand why anyone even suggests an Open Direct System. If it's not illegal where you live, it should be. Water may not stagnate in the winter when the system is all being used, but come summer it will. Even if you isolate it in the summer, when winter comes again, that stagnant water will get into your drinking water. It's insane to set it up without a HX to isolate the systems.

I'm no expert, but I've studied the options enough to have a strong opinion on this one.

Mike T., Swampeast MO

Jack

I'm NOT being flippant here--I promise--so please don't take this wrong. My situation is rather similar to yours, but qualified modern hydronic engineers are simply not available in my general area--they have to come from over 100 miles in any direction.

Most of the people here have no real problem with DIYers and are generally quite happy to help them.

The vast majority here are ALSO very concerned with producing QUALITY systems that are safe, comfortable and efficient.

The "base part" of the system you have is well-known for producing systems that give radiant a bad reputation. Both ethically and professionally most really want to have no part in such a system.

I'm not saying that they never work, but if you choose to do such yourself you really need to do your homework and study. Nearly EVERYTHING is available on the web if you take the time to search and learn how to filter out the garbage.

While you may believe your unanswered question to be simple, the answers would literally fill multiple books but with much still a matter of personal preference or opinion.

First, I would find out what (if any) assistance the company from which you purchased the "system" will provide. Tekmar is a good place to start researching control systems. Slant Fin has much technical info available at their website. There are a great number of indirect DHW products and most provide good information on-line regarding the proper use of their products.

There are many good books available at this site at "Books and More". The latest edition of "Modern Hydronic Heating" would likely be very good as well--any of the large on-line booksellers will have it.