Sunday, December 13, 2009

Zone 2- the hydronic wall.

Winter arrived hard and fast, bringing the issue of heat to the forefront. The in-slab hydronic system is working fabulously on the main floor, but the hayloft is usually 5-10 degrees cooler and in need of supplemental heat. Since our future plans call for solar-thermal hydronic heating, I want our system to be able to run at the lowest possible temperatures. That said, I opted for a 'hydronic wall' in the hayloft, instead of underfloor heating that requires somewhat higher fluid temps. To get started, I framed in a partition wall to divide the hayloft into two semi-private bedrooms (we decided not to extend the wall all the way up to keep the architecture of the high arched ceiling visible).
Then I built a "hydronic sandwich" using aluminum heat transfer plates between 'sleepers' of 3/4" foil-faced isocyanurate insulation.
With Lisa's help, we routed 1/2" pex tubing in a serpentine pattern through the wall, across the doorway framing, through the smaller side wall, then back to the starting point...then we repeated it in the second bedroom with a separate run of pex...whew!
Here is a closeup of the assembly:
Finally, ready for drywall, which is screwed into the studs being VERY CAREFUL not to puncture the tubing runs.... The aluminum plates help conduct the heat out of the pex tubing and into the drywall surface. The insulation 'sleepers' act as spacers between the drywall and studs, and help direct the heat out outward to the room. The drywall surface readily conducts the heat and radiates it outward to the room. By using this method rather than the more tradition underfloor hydronic installation, more BTUs can be delivered to the room at lower water temps...and it was a much easier and less expensive method in this case. The obvious downside to this method is the risk of puncturing the tubing with fasteners. I took a lot of pictures of the assembly and documented the pex locations so if we ever need to hang a picture on the wall, I'll know where not to pound a nail!


madmaxx13 said...

Why do you say you can get more BTU's from lower temperatures than an underfloor system?

Anonymous said...

If I had installed this as an underfloor system in this case, the wood flooring (plus Homosote underlayment and plywood subfloor) would create an insulating effect and reduce the BTU output of the hydronics by 50% or more based on published data I've seen. This can be partially overcome by increasing the fluid temp, but I want a system that can run at the lowest possible temps to best utilize the solar heated fluid.

Hope that answers your question,

laughingdragonwaterdragon said...

This is great! I'm going to seriously consider this as an addition to my 1960's floor based hydronics heating.

I know I'm losing heat to the ground and the pea gravel under the floor. And I have an old, inefficient boiler.

But I hadn't thought about putting in wall hydronics like this. Great design!

chemicalrefugee said...

We are a family of three living off in the semi arid regions of South Australia. Started off in the US (long story). My wife and I have Multiple Chemical Sensitivity which is why we live way out here, eat an all organic diet, and do not allow *ANY* VOCs or new plastics (etc) in the house, as they can result in seizures in my wife (and much pain in me).

Our house is a multi stage build with the oldest part being oer 100 years old. Roughly half of it has 3 foot thick stone walls (Aussie local general store) and the back half is the living quarters from when it was a store (we don't run one). It (unfortunately) is made from cement cinder block which is not good on keeping warm in winter/cool in summer.

As a result we are very cold in the winter (too cold for our health, especialy our daughters) and very hot in the summer. I have no problem with just taking off most or all of our clothes in the heat of the summer (better for the skin anyway) but we need WARMTH for the winter badly.

With all 2 to 3 foot thick walls in the old storefront which we intend on swapping over to a living space given time) and just ONE combustion wood stove in one room, I am thinking of getting a stainless "flu" tyoe of "Heat Exchanger" to move the heat from our wood stove into the rest of the house - using the old huge electric hot water heater in the rafters (which is going to be replaced with a non-electric choice by then) as that old tank is massive and perfect for a gravity feed down into radiators in the main living/sleeping areas.

For the smaller rooms I expect to just buy radiators, unless I feel far better from this illness via the detox work we do, (or the commercial ones are too toxic with petrochemicals for us). However for the largest room (currently not being lived in) I am interested in the idea of BUILDING a large radiator to mount against the longest wall (the old store front area).

We are thinking of carving off an extra area at the front door (to keep out the external air pollution & to store out "out-gassing" purchases in. Even removing this from the large front area, the wall in question would STILL be 7.5 meters long, and probably 2 1/2 foot thick stone. Good for absorbing heat into it.

I don't care if the radiator can be seen, just that it gets us warm. The wood stove will be one room over (through a 2 foot wall) tot he right, and all the bedrooms will be the other direction.

I know that getting the radiator INSIDE of the wall is better than putting it near the wall, but with these old stone walls that is very unlikely.

We have the extra complication of not being able to tolerate VOC / petrochemical items (building materials) at all.

Any new items from shops (they stink of perfumes and cleansers) always get out-gassed before use. Our new clothing can take a few months to be safe for us (and many washings). Some books take over a year.

Any plastics that are still out-gassing, and other -newly bought items, stay in a part of the house dedicated to out-gassing for our safety. Without doing all this, my Blood Pressure goes up to 200/100 and my wife has seizures and we both get horrible spasms.

Obviously we cannot build a radiator with any petrochemicals (VOCs).
Having more control of the materials is the one largest reasons for building our own. God only knows what they build them from, treat the insides with or paint them with.

Given the difference in PRICE for the parts,

Is there a seriously good reason for us to use copper pipe for a really large radiator of this type, instead of old fashioned IRON pipe? I am thinking about IRON with lots of fiberglass insulation wrapped around it for the main heat pipes radiator (perhaps iron for them too).

My parents house has an old style hot water radiator system. I has run now for almost 100 years without any need for even minor repairs - ever, and it has never had anything but water in the pipes.