cold boiler start

eric w

I've got a cast iron hot water boiler feeding cast iron radiators set up for cold boiler start off the thermostat. It's simple, but I wonder if there would be any advantage to configure it so that the boiler maintains temperature off an outdoor reset? On winter mornings, it takes about half an hour of boiler operation before the radiators start to warm up. I know I'd get faster heat if the boiler maintained temperature, but will I be burning more fuel? I'm sure it would be better for the boiler to stay warm, but then again there are thousands of cast iron boilers out there that live perfectly long lives set up for cold boiler start.

kevin

Outdoor reset.......

would work well in a lot of aspects w/ your CI rads... one thing not to do is set back the T-stat at night. It would take to long to recover. kpc

Cosmo

Here in Allentown PA we

have a lot of old gravity systems with a huge water content and alot of contractors replace the high flow circs with the 007's the boilers come with. Lately (when cust. understands and is willing) I have been setting these up so a big high-flow circ pushes the water around, and the boiler is piped as a secondary circuit with a thermostatic bypass too keep the boiler hot, and outdoor reset controlling water temp. This has been working pretty good, although the trick set-up would be a condensing boiler with outdoor reset...which brings another question. How many of you guys have used the Veissmann condensing oil boiler? I am still waiting to hear from the rep in my area...

John@Reliable

Eric, From a service point of view,

if the boiler is a newer one I would suggest maintaining temp. year round. I see to many cold start units (no tankless) that get all scaled up which mades cleaning almost impossible in time,also cuts back on heat transfer in the heat exchanger.The extra cost in fuel very little compared to transfer loss. Did work on one today which was only 10 years old ,but looked 25+. even after 3 hours of cleaning & new chamber had over 700' flue temp. due to lost heat transfer in heat exchanger. This will drop in time but some damage is done forever, Hope This Helps

ScottMP

Eric

Look into a outdoor reset control with a four way mixing valve for your system. My house has never been more comfortable.

The temperature to the radiators is tempered thru the mixing valve which is using a weather responsive reset. Just the right amount of warmth goes to the house. No more wild swings as the rads heat up and then over shoot the thermostate.

I do agree with a boiler maintaining tmperature even if its as low as 110. It will respond quicker and have less shock. As stated this will help with cleaning.

This photo is my house.

Good Luck

Scott

To Learn More About This Contractor, Click Here to Visit Their Ad in "Find A Contractor"

Boilerpro

I do the same...P/S with Esbe Themix

Works very well. In my opinion the only boilers that can be directly connected to a gravity system are condensing style or those with built in return protection. Maintaining the boiler at constant temp will likely result in shortened boiler life because every time the pump turns on the hot boiler will get a full load of cool system water and shock it(depending on how warm you keep the boiler) To keep the boiler warm in the summer I use standing pilot boilers with a stack damper. The pilot maintains the boiler at about 120F. Went back on two sp units Nat Gas with P/S piping and Esbe Thermix on boiler return and after 2 and 3 seasons in converted gravity systems the heat exchangers and burner trays were still as clean as when the boiler went in.


Boilerpro

Dave_4

outdoor reset control saves money

..over the whole heating season by backing off the boiler at non-peak times....i have the same setup at home (CI boiler, CI rads), & i'm convinced night setback saves gas usage over maintaining the entire house warm every night....it depends how well insulated your house is, windows etc....i use a tekmar controller that combines outdoor air reset with a heating curve matched to cast iron rads, so it prevents overshooting....the house drops to 60 degrees overnight & it takes 45 minutes to get over the 'pickup' load hump....but as soon as those cast-iron babies start humming, the comfort level takes a big step up, and the system cuts out 2 hours before setback and the radiators still put out plenty of heat...

Boilerpro

If you can recover that quickly

from setback I would think your heating curve is probably set too high, unless you have indoor feedback. A tightly set heating curve provides barely enough heat to maintain indoor comfort under typical conditions, so during recovery there is not a whole lot of extra capacity available in the system to recover temps. The difference between the air temp and the radiators will be higher during setback, so output per EDR is slighter higher, but this gradually diminishes as you get closer to comfort temps. Tekmar added the boost feature to thier controls to address this limitation. Just my thoughts./

Boilerpro