Some questions about another steam system, with pictures.

PMJ

When boilers are big enough to cycle on pressure you need to control both the burn and the wait times. That way no pressure can ever be reached. Even if they aren't that big it can help. It is really simple and really effective but for some reason this method never gets any traction here. Somehow the concept of running a boiler with a fixed on/off schedule inside a call violates some tradition around here and is immediately dismissed without thought. Really too bad, it is such an easy way out of a number of issues.

Here I see two guys actually cracking the door open with some thinking about this. How encouraging.

Shalom

ethicalpaul said:

Who's taking bets on this one? Sorry to be flip, but I've seen this story dozens of times and I've only been around here a couple years.

I told my mom to have it written into the contract. She works in a real estate consulting office which deals with landlords trying to get tax abatements and/or rent increases for things like new boilers, so she's seen plenty of contracts like this; she'll know how to have it worded.

Still no proof that it's actually going to get done, but at least she's got recourse if it isn't, especially as she's paying it out over time.

Jamie Hall

It's really a fascinating question of control strategy, and we've seen quite a number of excellent experiments or solutions here on the Wall from time to time.

What one is trying to do, of course, is figure out the best way to modulate a system -- which may or may not be simple to modulate.

The controlling parameters are simple enough -- structure heat loss and desired interior space temperature, that's all, really. But...

Thinking about it.

Chris_L

I am not sure a thermostat couldn't know when the Pressuretrol tripped. It depends on where the Pressuretrol is in the circuit.

If it is the last control before the gas valve, and the thermostat is calling for heat, and there is no current flowing (which the thermostat could monitor) the thermostat would know something downstream opened the circuit.

I use a fixed on/off schedule for my tenant's oversized boilers--9 minutes on/14 minutes off--but it only starts after the pressure reaches about 6 oz. (measured with a pressure sensor and controlled with a microprocessor) after the thermostat calls for heat.

I could drop the pressure sensor entirely and just start the on/off process on a call for heat. The only problem with that is the first burn takes a lot longer after the boiler has been off for a long time (e.g. > 4-5 hours) and everything has cooled down. The apartment would take that much longer to heat up in the morning after the setback my tenant's use.

PMJ

Chris_L said:

I am not sure a thermostat couldn't know when the Pressuretrol tripped. It depends on where the Pressuretrol is in the circuit.

If it is the last control before the gas valve, and the thermostat is calling for heat, and there is no current flowing (which the thermostat could monitor) the thermostat would know something downstream opened the circuit.

I use a fixed on/off schedule for my tenant's oversized boilers--9 minutes on/14 minutes off--but it only starts after the pressure reaches about 6 oz. (measured with a pressure sensor and controlled with a microprocessor) after the thermostat calls for heat.

I could drop the pressure sensor entirely and just start the on/off process on a call for heat. The only problem with that is the first burn takes a lot longer after the boiler has been off for a long time (e.g. > 4-5 hours) and everything has cooled down. The apartment would take that much longer to heat up in the morning after the setback my tenant's use.

The cold start problem with this method is solved with one remote temp sensor. It overrides the timers and burns straight till a make so the first fill is the same every cycle no matter the off time. The fixed on/off schedule begins after that.

The next level up from this is having the fixed on timer be an amount after the remote temp make and the fixed wait timer be an amount after the same temp sensor opens. With this method the burn/wait combination changes itself with the conditions.

This second one is what I do now...plus natural vacuum. I made no changes to the timers this whole season.

Shalom

So I finally got the pictures of the new boiler. Actually got them in October but didn’t get to post them yet. What do y’all think? They do it correctly?

(I just realized I don’t see the pump for the basement hot water loop, maybe it’s behind, could be that copper pipe I see near the back of the left side is part of it.)

Jamie Hall

Not bad. Not bad at all. How does it work?

EBEBRATT-Ed

The only thing I notice is the location of the make up water going in the Hartford loop. Not crazy about the location but may not be an issue

Shalom

I spoke to her tonight. She says it warms up quickly, she’s comfortable with the thermostat at 69 when she used to have it at 71, and it’s quiet. She said she doesn’t really pay attention to if some rooms heat up faster than others, and she hasn’t checked to see if the bills went down, but she’s going to look into it.

neilc

skim port ?
I don't see one