Constant flow

mike chacon

I have a cast iron boiler connected to cast iron radiators with 1 thermostat control- one zone. What are the advantages as well as the disadvantages on letting your pump run continuously, with your burner coming on and shutting off solely based on a demand for heat? Will constant flow allow for heat stored in radiators in off cycle to be distributed thourgh out home (ie. - to other radiators ). allowing for even/better heat distribution?

gennady

constant

flow is a good thing, just do not bring water temperature return below 140F

gennady

duplicate

duplicate

gennady

duplicate

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gennady

duplicate

duplicate

mike chacon

Constant flow

If boiler is off what difference does it make it flow through boiler is under 140 degree?

gennady

low temp protection

there should not be water flow trough the boiler with water temperature under 140F entering the boiler with boiler firing. flow can start if temperature of water in the boiler exceeds 140F

Paul48

?

Oil or Gas?

gennady

oil or gas

does not matter

Paul48

Figured

gas probably has a post-purge that would remove any residual flue gases, and eliminate the concern for condensation. Maybe a wrong assumption.

gennady

post purge

it will condense when boiler is on, oil or gas.

Paul48

Right

I was only considering shutdown. Then that would prohibit constant circulation, with a cast-iron boiler?

gennady

primary secondary?

will solve your problem. detach boiler from system.

nicholas bonham-carter

Avoiding condensation

I think it's only during the firing that the water temperature should as quickly as possible be brought above 140 deg.

For every pound of hydrocarbon fuel burnt, there is released one pound of water. This water vapor can then condense onto the cast iron, and as it also has sulphur dioxide in the exhaust, can make sulphuric acid. This is not a good chemical for the cast iron to be in contact with.

Prolonged firing of the burner with the water inside the sections cooler than 140 degrees will constantly bathe the metal with this acidic mixture with disastrous results!

This condensate when coming out constantly from a condensing boiler has to be neutralized as far as its acidity, or will eat out the drain line into which it runs , with disastrous results!--NBC

mike chacon

Boiler protection

Is boiler protection only necessary when boiler is fired up? With constant flow, I hope to redistribute heat in high mass radiators to 2 panel radiators in burner off cycle.

Gordy

How about some pics

Of the boiler room please to see how things are piped. P/S, or boiler bypass etc.



NBC explains boiler condensation, and the need to minimize



It's a little more than running the circ constantly. You will over heat the space if the t stat is satisfied, and the boiler happens to be near high limit in the heat call you will purge the hottest water 180* into the emitters. Over heating the space You will need outdoor reset, and piping strategy.