Hydronic System Modifications

BrennanU

Hi everyone,

First off, some background on my system... I have a 1970s era Crane oil burning boiler (85200 BTU) heating my Northeast Ohio home. The system has 4 different finned baseboard zones, each with a manual flow control valve at the start of the loop. One covering the basement and living room (~37ft of baseboard). A second covering the kitchen and breezeway (~39 ft of baseboard). A third covering the two upstairs bedrooms (hard to measure, I have it packed full due to the remodel). And a fourth covering the 1st floor master and corresponding bathroom.

I've been doing some major remodeling and I've soldered in a couple of ball valves to remove the fourth loop while I make some changes. As of this moment, the only thing left of this zone is a 3/4" copper supply and 3/4" copper return with a ball valve and a stub of pipe on either end.

In the new master bathroom I am considering adding some form of in-floor heat. From what I've read, my ~180deg water (that is what my high limit is set to, in a typical cycle, I don't think it usually gets up to 180) is a little warm for typical radiant floor heat. I found a product from Ultra-Fin that allegedly convects air within the floor joist cavity to heat the floor. Does anyone have any experience or feedback about using this type of system?

A couple more questions revolve around the finned baseboard I plan to reinstall in the bedroom (~12').

First off, I figure that I should split these out into two different sub zones. The bedroom is actually a fairly comfortable temperature without any baseboard (I do recognize that we are not in the dead of winter yet). As such, I figure that I may want to throttle the bedroom down more than the floor heating. Any problems if I split the 3/4" feed to this zone and add two extra manual flow controls?

Also, due to some interesting construction, it is going to be a pain to get copper up to the baseboards (the house had the basement added later, so the basement walls are set back a couple feet from the walls on the first story). I was thinking of using some of the extra 1/2" oxygen barrier pex-a from the bathroom floor heat for those baseboards. The rest of the house is minimum 3/4" copper by the time it gets to a specific zone. For a short run (~12' of baseboard), would it hurt anything to feed the 3/4" baseboard with 1/2" pex? As I mentioned, the bedroom is already fairly comfortable, and if anything, I would prefer the bedroom be a little cooler than the rest of the house.

Thanks for any suggestions you can provide!
-Brennan

EBEBRATT-Ed

With only 12' of baseboard in the bedroom 1/2" pipe/tubing is fine. 12' of baseboard is only about 7000 btus or .7 gpm of water. 1/2" pipe is good for 1.5 gpm pex is probably slightly lower so you are good there. I would

But for the radiant zone you will need to put a mixing valve on that zone to get the water down in temp 180 is much too high

BrennanU

Thanks for the insight.

One other question, the manual for the convective heat panels specifically mention the panel spacing for 180deg water. I believe their logic is that they are convecting air in the joist cavity instead of heating the floor directly. 

In this case, I should be ok without a mixing valve, right?

EBEBRATT-Ed

Not farmalier with ultra fin. Others will comment @Zman

Zman

I have not worked with Ultra-Fin. It appears as though they are designed for high temp if high output is required. https://s3.amazonaws.com/s3.supplyhouse.com/manuals/1249544874360/UltraFin-Brochure.pdf

Output requirements higher than 25btu/ft are pretty unusual, I would think that from a comfort point of view mixing would be a good idea.

hot_rod

yes the ultra fun could run 180 as long as the tube is rated for that temperature. It is a nice compliment to fin tube systems. Follow their installation instructions especially the need for the tube to expand. No reason it couldn’t run lower temperature, as long as it covers the load