boiler (heating) temperature

[j j]

we're heating the house using hot water baseboard heaters. the water is heated by an oil burner.

there's a thermostat that turns off the burner when the water is above a certain temperature, regardless of what the thermostat says.

right now the temp is set to around 175 celsius. the thermostat goes higher. what happens if I put it at 200? is there a max temperature for a water system? can anything melt? (the pipes are cast iron, it can't melt but is there anything else that could be damaged?)

also, if I'm trying to eliminate high temperature swings (house has heat inertia, by the time the main thermostat tells the burner to turn off, the water is hot and will continue to warm up the air and the temp will increase further) should I set the burner thermostat lower? (making the water go to a lower max temp and warming up the house less. by my logic this would make the burner run more often to keep the house at the same temp, but for shorter periods of time, and the swings shouldb e lower, but maybe I'm wrong)

[HA HA Budys Here]

I doubt that. 100 degrees celcius is boiling.

I wouldn't lower the boiler temp, I would restrict the flow through each zone instead.

[Stormin Mormonn]

First, water boils at 100 celsius, so I suspect your boiler aquastat is in farenheit.

Second, the problem you're noticing is cause by the time the thermostat notices that it's hot enough, the radiators are all full of hot water.

I'd be tempted to try tweaking the heat anticipator on the thermostat. If it still bothers you, a couple degrees lower on the aquatstat might help. That way, when the thermostat is satisfied, the water in the pipes won't be as hot.

I'm used to seeing 140 to 160 for aquastats.

[SQLit]

As a wild as guess what would happen if you increased the pumping volume. Or start the pumping sooner. Screwing around with a boilers set points IMO should be left to the people that work on that equipment, which I do not. Be careful with the controls on these beasties. They can bite back.

[Edwin Pawlowski]

Holy Shit, get out of the house! At 175C you will be near 130 psi of steam. The heater is rated for only 15 psi of water. At 200C, you will be approacing 200 psi. That could kill you! ! ! if it blows up!!!

Yes, about 85C At 100C it becomes steam. What? You say you meant F???. Much better.

No, the systems can handle it.

Thee is some logic to what you want to do. Turn the high and low set point back by 10 degrees and see what happens. Then another 10 degrees. I don't know what the system was designed to run at so I can't make a definite answer. Ed

[j j]

OK, I guess it's Fahrenheit. I just know it's 175. Being in Canada I assumed it was celsius, since we're metric, but I guess it is an old boiler...

so 200F is about 93 celcius. what presure would the system be at when the water is 200F?

with the water at 175F, the pressure is about 13PSI.

[Stormin Mormonn]

You, I like!

[EL]

Are you sure the temperature settings are Celsius? If so you have an old pressurized steam system. At 175 C the pressure will be 130 psi. At 200 C the pressure will rise to 226 psi. Be sure that your system can take this pressure before you make any adjustments. Live steam is nothing to play with.

Boden

j j wrote:

[mark Ransley]

To reduce temp swings adjust anticipator or get a quality thermostat. I have 2 Lux units , their best . One on forced air one on Hot water heat Neither one is as good as my old honywell, And there may be better than honywell.

[John_B]

I have had experience with two houses which used coils in the central heating boiler to heat water for bathing, dishes, and laundry without need for a storage tank.

The first one used steam to heat the radiators. During the summer when the aquastat controlled the operation of the burner, the hot water temperature was reasonable. During the winter when the thermostat told the boiler to fire up and make steam, we sometimes had hot water near boiling.

Now I am in a well insulated house with hot water baseboard heaters and a "domestic hot water" coil in the boiler. I find that the temperature swings are quite acceptable and hardly noticeable.

I like your idea of REDUC> we're heating the house using hot water baseboard heaters. the water is

[HvacTech2]

Hi Stormin, hope you are having a nice day

On 02-Dec-03 At About 02:06:04, Stormin Mormonn wrote to All Subject: Re: boiler (heating) temperature

SM> From: "Stormin Mormonn"

SM> First, water boils at 100 celsius, so I suspect your boiler aquastat SM> is in farenheit.

SM> Second, the problem you're noticing is cause by the time the SM> thermostat notices that it's hot enough, the radiators are all full SM> of hot water.

SM> I'd be tempted to try tweaking the heat anticipator on the SM> thermostat. If it still bothers you, a couple degrees lower on the SM> aquatstat might help. That way, when the thermostat is satisfied, the SM> water in the pipes won't be as hot.

SM> I'm used to seeing 140 to 160 for aquastats.

And here we have another example of someone who should't try to answer these questions.

-=> HvacTech2