Limiting Heat in Split Zone. Themostatic Valve?

Post by **Richard S.** » Sat. Dec. 05, 2015 1:16 pm

It's almost up to 64 degrees upstairs above my Gram's. She has it set at 74 downstairs.

60 degrees on the other side so it didn't come up much at all on the other side, set at 70 downstairs.

She's on the sunny side of the house, not sure how much is from downstairs heat. I don't think I'm going to be able to tell how well these these things are working until it gets cold and stays cold for a few days.

Post by **Rob R.** » Sat. Dec. 05, 2015 3:55 pm

There may be a few degrees difference between a thermostat on the wall and a bulb laying on the floor, just due to the difference in height. I agree that the real story will be told once it gets cold.

How is the NG boiler working out?

Post by **Richard S.** » Sat. Dec. 05, 2015 5:59 pm

Rob R. wrote:There may be a few degrees difference between a thermostat on the wall and a bulb laying on the floor, just due to the difference in height. I agree that the real story will be told once it gets cold.

The thermometer is near the ground too. The install instructions suggest mounting it directly under the radiator but it would seem to me that kind of defeats the purpose of having the bulb.

How is the NG boiler working out?

She has no complaints, bill was reasonable all things considered. I had to go and adjust it.

The aquastat is electronic one from Beckett. They never set a low limit, hi is set a t 180. Plus there is some kind of economizer on it that does it's magic and apparently will set the hi. The boiler temp I would guess can drop to ambient temp, doesn't really matter much because it heats up really quick .

The problem with that is the thermostat on this side doesn't kick the boiler on, I noticed a few times the heat didn't seem that high. Went and looked this afternoon and it was pushing around 100 degree water. Set the low at 120...

Post by **Rob R.** » Sat. Dec. 05, 2015 9:15 pm

It is pretty standard to shut the low limit off if the boiler doesn't have a tankless coil...but they should have checked the wiring to make sure each zone could signal the boiler to fire. It would not be hard to change it, but once the boiler starts getting more heat calls it might not matter.

120 is pretty low for a gas boiler. I am pretty sure the flue gasses from NG condense around 135 degrees. I would set the low limit at 140 or even 150.

Post by **Richard S.** » Sun. Dec. 06, 2015 12:55 am

Rob R. wrote: but once the boiler starts getting more heat calls it might not matter.

That's what is happening most of the time. I'm going to have to check her bills to see if there was spike in electricity after it was installed last year. I really haven't been staying here at all since so I really don't know.

120 is pretty low for a gas boiler. I am pretty sure the flue gasses from NG condense around 135 degrees. I would set the low limit at 140 or even 150.

I read that in the manual for the aquastat, probably should read the manual for the boiler.

If the boiler recommends it that's what I'm going to do, set it and forget it.

They never changed the relays, they are almost 50 years old. One makes an awful buzzing sound. One big problem here is because of the time of the year if I start messing with stuff and something goes wrong I'll never hear the end of it. Putting in these valves at this time took a lot of convincing. Like I said she was telling me she'd have to go to motel. LOL

Post by **Richard S.** » Wed. Dec. 09, 2015 3:26 pm

Manual for the boiler says you should have a lo of 130. I was going to set it at 140 but the Lo limit won't let me set it above 120, why would that be?

Diif on both the hi and lo is set at 10, hi is set at 180. Economizer is on and eff. is set to med.

Sting · Post by **Sting** » Wed. Dec. 09, 2015 7:26 pm

is this a modern condensing NG boiler? this would explain the low temps

put those thermal sensors of the non-electric valves up off the floor outside of the thermal stream of the radiation

then System Balance

Post by **Rob R.** » Wed. Dec. 09, 2015 7:37 pm

It is an atmospheric NG boiler.

Post by **Rob R.** » Wed. Dec. 09, 2015 8:07 pm

I just read the manual and can't see any reason that you would not be able to adjust the low limit to a higher number. Maybe try shutting the economizer off and see if that makes a difference? If not, I would call Beckett.

Post by **Richard S.** » Thu. Dec. 10, 2015 2:12 am

Sting wrote:is this a modern condensing NG boiler? this would explain the low temps

Sting honestly I have no clue, the manual is back down in the cellar. The manual says the lo limit should not be set lower than 130 to prevent corrosion caused by flue gases. That's all I know.

Otherwise the low temps are not a big deal other than the thermostat not kicking on the boiler on the one side. It heats up really fast.

Rob R. wrote:I just read the manual and can't see any reason that you would not be able to adjust the low limit to a higher number. Maybe try shutting the economizer off and see if that makes a difference? If not, I would call Beckett.

I haven't read anything in there either to indicate why it won't go higher. Tried turning off the economizer before, should have mentioned it. Now that I'm thinking about it has to be something with that, perhaps I didn't get it turned off and though I had it off. the manual says the high and the lo have to be set apart the diff's +5 degrees which would be 25 degrees. The economizer says it's setting the hi limit at 145, 120 + 25 =145.

Sting · Post by **Sting** » Thu. Dec. 10, 2015 11:20 am

OK as Rob posted above - you must run above condensing temperatures so keep the boiler above that - I recommend no less than 140 but your mileage may vary

if you need cooler water - lets say retrofitting a historic house that was originally designed by an old dead guy to run by gravity = then build a temperature reducing loop out of several fittings and a couple of valves and pump that water.

Once you begin to limit flow at certain radiation points - well other points will just get more flow = more energy = more heat in the room. Now is a good time to balance that flow so the points not controlled by any non electric valve doesn't get too much water.

I used to preach on a soap box so if you have a moment search system balance in my old threads and you will get the comfort and economy you are looking for

Post by **Richard S.** » Thu. Dec. 10, 2015 4:31 pm

Sting wrote:
if you need cooler water - lets say retrofitting a historic house that was originally designed by an old dead guy to run by gravity = then build a temperature reducing loop out of several fittings and a couple of valves and pump that water.

No, it replaced a coal boiler in my Grandmothers house. She's working on 98 and the last Great Grandkid just went into the military so there was no one too really take care of the boiler every day. I come down and stay with her occasionally because I can... Always had pumps, at least for 40 years.

Once you begin to limit flow at certain radiation points - well other points will just get more flow = more energy = more heat in the room. Now is a good time to balance that flow so the points not controlled by any non electric valve doesn't get too much water.

Everything is working fine as far as that goes, they are keeping the heat from running into the upstairs and I was able to get heat too flow at a higher room temperature. I only need to get then adjusted to open at 55ish. It simply hasn't been cold enough out to do it, there is apparently a lot of heat migrating upstairs. The set point on them looks like it's going to be about ten degrees off what they expect on their chart but as long as they are consistent and open around 55ish or little lower is my only concern. There is plenty room to open them up if you want it want it warmer.

On the trouble shooting chart for overheating(based on the set point) it says different pressures on the feed and return could cause this and because of the configuration I'm guessing that is why they are not jiving with the chart set points. Like I said as long as they are consistent I really don't care what the dial says, It's only numbers and are approximate.

Sting · Post by **Sting** » Thu. Dec. 10, 2015 8:56 pm

good deal

Sorry I wasn't much help - sounds like you got this

Post by **Richard S.** » Mon. Jan. 04, 2016 1:22 am

Well it's a success as far as I can tell. Haven't been around Gram's house since a little while before Christmas so I decided I better take a ride down there this morning since it was first morning the temps got really low. 55 on her side and 51 on the other side. Pump was running when I got there and sure enough there was heat flowing through the pipe. Same thing on the other side.

Post by **Richard S.** » Thu. Jan. 28, 2016 9:57 am

Still unable to get the aquastat past 120. The manual for the boiler says it should be set at 130, the manual for the aquastat says it should be set between 140 and 150 and I'm mentioning this because that would indicate it can go past 120. The only thing in the manual I can find why it won't go past 120 is custom stop that can be set at the factory. e.g. the boiler manufacturer ordered it that way.

The plumber who installed it was here, he can't get it past 120 and is telling me the aquastat was shipped with the boiler.

The controls for the boiler were never included in the original contract and he's says there is no way to set them up so the second zone will kick the boiler on. These are Mercoid relays and about 45+ years old. Haven'tlooked at them myself and I'm just taking his word for it because he's offered to give me used relay but that will only partly solve the problem.

I guess my only recourse now is contact the boiler manufacturer to find out why there is discrepancy between what the manual says and the aquastat limitations.