Boiler temperature

Lothar

Correction: Photos 1 & 2 were old. The pump for the radiant floor was relocated and is the bottom pump in photo 3. See the updated boiler photo.

All four pumps are TACO 007-F5 and have no reference to IFC on their label. The pump at the boiler feeds the coil in the air handler and returns (behind pump with white insulation) to the boiler. The two PEX lines are the feed and return from the radiant plumbing in photo 3. There are no “Tees” off the view of the photos.

The system may not be the ideal set-up but it does perform well. It has no problem heating the entire house when it is 5F outside. My basic questions concern the set point for boiler. Can I set the aquastat at 190F and let it sink up over 210F without worrying? The boiler has a stated max of 245F but what about the rest of the system?

When all 3 zones are pumping, can that cause a big temperature differential in the boiler?

Lothar

Background:
When I added two radiant floored rooms to my existing house, I replaced my oil-fired forced hot air furnace with a boiler and air handler. The new system has 3 zones; 1 zone for the air handler in the main house and a zone for each radiant floor room). The radiant system has a water temp design point of 145F on 0F degree day and an outdoor sensor that uses a mixing valve to resets a lower radiant water temperature as the outdoor temp increases. The aquastat on the boiler is set at 180F with a 30F differential.

Issues:
1. When only the radiant zone(s) are calling for heat, the gauge on the front of the boiler approximately reflected response at the aquastat set temperatures. The burner shuts off at about 180F but the temp continues to climb above 200F. Is this normal? How high can the temperature get before I should be concerned?

2. When only the hydronic air handler is calling for heat, the burner shuts off below the set point (about 170F) and the boiler temperature slowly decreases. What kind of correlation between the aquastat temperature on the back of the boiler and the gauge temperature on the front should be expected?

3. When all 3 zones are calling for heat, the burner turns on about 135F-145F and shuts off at about 150-160F. The colder it gets outside, the radiant is demanding a higher temp, and the burner cycle gets shorter, about 10-15F despite being set to 30F. Is this due to the larger flow through the boiler (3 zone pumps running) and the aquastat sensing a different temp than the gauge? Should I be concerned?

Couderay

Different temperatures

I wish I had more to offer you but maybe a little more info on your boiler piping and kind of boiler would help. How is you radiant set up done. Where and how many temperature guages do you have on the system.

Lothar

piping

Thanks for responding. See attached photos.
The boiler is a Biasi B10-4 (126 gross MBH) (www.qhtinc.com) with a Riello burner.
The radiant is pex under the sub-floor for the 1st & 2nd floors of the 16’ x 24’ addition.
The green box in photo 3 is a Wirsbo proMIX 101 that adjusts the orange/gray mixing valve based on the outdoor temperature. It also senses the water temp downstream of the mixing valve and the boiler return temp (currently set to off).

MIke_Jonas

Pumps?

In the last pic, is it OK to mount the pumps with the shafts vertical like that? I thought they all had to be horizontal.

Weezbo

wow.---

it was 5 :15 when i noticed that i had not made it to work today fixing things along the way ,working left handed to that point in time...you have lots of things to consider, just by looking at the system. i will get a cup of coffee...and think the picture a bit..what i say isnt, "ok this is all wrong ", it is "ok where to go from here to get there".

a brief answer to your question is the temp rise in the boiler is about the equivalent of throwing breaks on a train..sure the breaks are on buh the momentum will continue to carry the flowing train forward ..a while.

#2 the air handlers are losing BTU "Passengers " on the train. rapidly . far more so than the radiant..

#3 when everyone is bailing from the train and all the new passengers are getting on board that entire operation can only occur just so fast, however ...like i said i need a cup of coffee.

one cup of coffee didnt help much..

on the first picture there are 2 circulators...does one go to an indirect hot water maker? why is it turned off?

in neither picture #1 or 2 or 3 is it particularly clear as to the whereabouts of a return line..what can be seen looks like a dead headed pipe with a couple couplings a couple 90's and a "T" that has a run to nowhere,and another valved off. does your boiler Have a return? because if it doesn't , you have a remarkable system indeed...

picture #3 seems to have a supply and return just a few quick thoughts , one go back and make up the Wirsbo fittings so that the ring meets the brass and the pipe is a 16/th " shorter....spin the circs so that they come off at right angles 90 degrees to where they live now,... the double bull headed "T's" sure dont help with the comprehension of flow ... they may be a little ahead of their time in that formation, let me ask you a question,...

are those IFC circs or high head circs? Mark just made the case for 20 PSI while true i still think that they are better off in the long run ,living 90 degrees from the present positioning.

my other thought about the circulators is if the circulator at the boiler operates the flow out of the boiler to the radiant board, whats the rational behind the additional circulator (currently motor down...) it seems different... are the supply and returns finding their way back to the boiler through closely spaced "T's" off view of the picture ? three way mixing valve?

[Deleted User]

Yes and no...

Vertical with the can over the pipe is acceptable in the Taco I&O manual PROVIDED that the system is operated at greater than 20 PSI (I think...).

With the can below the pipe, no, it acts as a dirt trap and exerts undue strain on the bearings...and short life expectancy.

ME