Either the Boiler is to small, the water temperature is to low or the flow is to slow. If the boiler is cycling on and off then it is large enough, if it does not turn off it is undersized. If the water temperature is hot going into the tubes, 110° to 120° for concrete, 130° to 140° to for staple up, 110° for Gypcrete. Check this at the point it goes into the floor. If the water coming out of the floor is more than 20° lower than going in the flow is low. Low flow is caused by a pump with a lower head than required or a restriction such as a mixing valve or air in the system. See page 44 also.
SMALL BLACK RUBBER TUBING
This tubing comes as individual 3/8" tubes or with a group of tubes with a web between them.
This tubing is a problem, I have worked with several of these systems over the years. If the tubing is installed with a cast iron boiler or has any steel or iron in the system, you have a real problem with rust and also an algae that feeds on the iron and oxygen that the tubing absorbs. This plugs the tubing over time and is difficult to remove. This material is ethylene-propylene-diamine or better known as E.P.D. or SoloRoll. It was developed for roof top solar collectors for heating swimming pools. It must be installed with S.S. boilers or standard water heaters and only brass or copper manifolds and fittings. These systems start to fail in as little as ten years if there is any ferrous materials in the system. Systems with EPD that are starting to plug up can sometimes be saved by blowing the tubes individually out with compressed air, removing all ferrous products from the system and treating the system with a fungicide.
PROBLEMS ASSOCIATED WITH POLYBUTYLENE IN A RADIANT HEATING SYSTEM
Keep the pressure below 30#, keep the water temp below 140. Use only brass fittings. The big problem with PB is the oxygen absorption, the tubing will absorb oxygen through the tubing walls. The tubing must not be connected to a cast iron boiler, the boiler will plug up in about ten years. Worse yet the tubing will grow crud from the iron oxide and available oxygen. The tubing will need to be flushed with an fungicide and high pressure to wash the growth out. And the tubing will need to be hooked up to a stainless boiler or separated with a stainless steel heat exchanger.
I NEED YOUR HELP. I contracted 8/05 with a man who represented himself as an experienced radiant heat HVAC contractor. He proposed to install the heat in my existing 3100 Sq. Ft. bi-level built 1974; lower level concrete block. upper level frame. We took out elec. baseboard heat. He proposed staple up between joists w/ emission plates for upper floor & Wirsbo "QuickTaks" fastened to the concrete slab on the lower level. Peerless boiler 199,000 Btu's, 2 zones. He quoted $18,500. The bottom line is that he had received $11,100 from me b time he started. He then introduced me to two 19 yr. old guys and left for vacation. A week later he checked in. The 2 guys were working 2-3 hrs. a day and weren't doing anything as he described. They finished the upper floor by the end of the 2nd week and never came back. I wasn't able to find anyone who would finish the lower level till January and I didn't have any design or materials. The 2nd HVAC guy was only willing to install. Well, he installed tube in Joist Trac, and I had to construct a sleeper. When it was done the finished floor height wouldn't clear the new entry doors, so we tore it out. Then he installed 3/8" plywood over the 1/2" plywood that I installed over the existing slab and he had my carpenter use a router to cut grooves in to accommodate the 1/2" pex. The carpenter charged $2000 for sleeper then $4500 for the 3/8" plywood and routing. The HVAC guy charged me $4571 for the first installation then $4121 for the second. When we started it up the boiler leaked. The 2nd HVAC guy didn't want to be involved with the boiler & controls, so I finally found a 3rd HVAC guy to tell me what was wrong. He did the heat loss calcs. but he doesn't want to be involved either. I took the 1st guy to small claims & asked for $5000. I was awarded $1860. He appealed and is suing me for another $3200, and I already paid a lawyer $3500. I still don't have heat. I could give you detailed photos and descriptions of the house site. Is there anything you can do for me or someone you can refer me to. Respectfully; Linda.
I offer a fee based design service for radiant projects, complete instructions, material list, assembly diagrams, tubing layout, material specification and troubleshooting. I concentrate on simple and efficient systems, this service can save thousands and more importantly eliminates potential problems. Fred Seton E-mail