Update - December 2005
In the past year or so, I have received several queries about my heating system, and hopefully I can address some of those things here. The material was from Radiant Technologies Inc in Bellport, NY. Although I can find URLs for them in Google, I can't get them to work (www.rtisystems.com). All of the material was actually delivered via a local heating distributer. The initial engineering and consulting was from Paul Ross Associates - I think he may have a web site now at http://www.hydronicalternatives.com/index.html.
Based on my 10 year old notes - the entire package (controls, tubing, radiant panals, pump, etc) cost about $5,500. The distribution manifold is made by Stadler (http://www.stadlerviega.com/index.asp. The temperature controller (it has temp sensor outside, another on the supply lime, and drives a mixing valve) is a Danfoss ECL 9304 (http://heating.danfoss.com/) - I imagine that their product line has advanced over the years. The 4 way mixing valve ad motor to control (type 62) is made by ESBE (http://www.esbe.se/)
Original Posting - circa 1995
In around 1989 or so, my old coal to oil conversion steam boiler died,
and it was replaced with a new powerful gas fired steam boiler. Unfortunatly,
this was too much for the old single pipe steam system, and a major problem
with banging resulted. An attempt was made to retrofit a condensate return
loop, which reduce the banging, but ultimatly, not enough. Shortly after
the 1 year guarentee expired, a 1" cast iron fitting failed. After replacing
this twice, I finally decided to convert from steam to forced hot water.
This involved converting the steam boiler to forced hot water. One of the
aspects of the new system, is that the circulator allways runs and a computer
controlled mixing valve is used to control the temperature of the water
going through the radiators. This temperature is determined by an outdoor
sensor. The mixing valve is the black box where the copper and iron pipes
come together. In addition to the mixing loop, stubs were left on the
input and output of the boiler in case there is a need to add a high
temperature loop in the future. The water level in the system is maintained
by an autofill valve on top of the red expansion tank. This then feeds into
an air extractor that automatically removes air from the system.
From the mixing valve, the water is pumped past a temperature sensor and into
a distribution manifold. Each zone on the manifold has a flow control
(the red knob) that allows for balancing zones (in case one zone is getting
too much heat.) In general, balancing is not needed as the amount of
heat in each zone is set by the amount of radiant heat in the zone. Once the
water is sent to the zone, it returns to the return manifold (the upper
manifold) where it sent back the the mixing valve. Each of the return
zones has a zone control valve that allows the zone to be turned on or off.
This allows for an entire zone to be turned off when not needed. The blue
manual controls have since been replaced by electrical controls.