How do I zone a Hot Water System?

Matt_58

Frank & Big Ed,

Thanks for your advice. I had thought that I would need to split the line and run more pipe. Since this is the case and I will be looking at spending some time and money already; do either of you think that it might be time to convert my first floor (baseboard) to in floor heat? I have 3/4 inch oak floors that are over 7/8 inch x 12 inch plank sub floors. The house is just over 100 years old. Is this a project I should consider?

Matt_58

How do I Zone a Hot Water System?

Hello,

I am new to this fantastic website and am looking for some advice. I have a hot water system. The basement and second floors have free standing radiators and the first floor has hot water baseboard heat. The first floor was at one time populated with radiators and was later converted, so now I only have one radiator on the first floor, in the kitchen.

My problem is this, if I set my "Honeywell No. 9" thermostat 60 degrees for the first floor, the second floor is 73. I have a single trunk system with one main line that feeds all of the radiators and baseboards. I would like to zone my system for better temperature control; how do I go about doing this and/or is this possible with my system? Please let me know if there is any additional information that you need or would like. And thank you in advance for all of your help.

Frank_62

your baseboard requires 180 degree water to heat and the free standing radiators (cast iron) require 150-160 the thermostat is on the first floor being satified by the baseboard at higher temp causing the radiators to overheat. You would have to break out the supply and return for basement and second floor and run a seperate feed and return back to the boiler or one loop for each using monoflow t's connected to the supply and return which you would have to extend to accept them with pumps or zone valves and thermostats for each zone plus a relay like a taco 503 or seperate relays for each so on a call for heat you can bring in the pump and burner. you could also move the thermostat to the second floor which would satisfy sooner but may leave your first floor to cold. breaking it all out is a big job and costly but hte results will make you happy just one more thing if thi is a new problem because it does seem like a big temp swing when the boiler is running put your hands on the supply and return side of the boiler and see if the water is leaving and coming back hot look at the temp gauge on the boiler and try and make an assesment if not hot bleed the radiators you may have air in the system not uncommon hope this helps good luck

Big Ed_4

Boiler bypass

I agree with Frank with seperating the three floors into three zones. As Frank stated the cast iron radiators run at a lower temperture. You will need to install a boiler bypass for the two cast iron zones. The boiler bypass allows returning cooler water from that zone to mix with that zones supply to temper down the supply temperture. Set the boiler to baseboard disign terperture and adjust (lower) the cast iron zone.

Also..Every floor or wing needs to be zone seperately to achive proper control because they will have different heat losses or different loads....

Mark Custis

You could

The Radiant Panel Association has R-values for different types of wood.

To make it work you need more Rs under the staple-up than the value of the flooring.

Big Ed_4

Old Flooring

Beaware of any meteral that was used between the oak and sub floor. Tar paper or horse hair matting may stink if heated.....

Also radiant will run on a lower temperature then cast iron radiation. The bypass will be needed on the radiant.....

Frank_62

I wouldn't be messing with radiant heat in a 100 year old home, I think your looking at a real nightmare. For starters you probably have to go with a different boiler depending on what you now have,so it would accommodate the lower temps. If you have and older but functional boiler in that 100 year old home even if its been insulated new windows ect. you may be better off to rip out the baseboard and go back to the cast iron radiators maybe not as pleasing to the eye but great heat. Tweek your existing boiler or look into a higher effeciancy unit but reasonable like a biasi,trio,buderus,weil mclean you'll be toasty warm at a reasonable price all running on one zone the best keep us informed