circ pump question

allenh

We have a boiler in a basement, running 2 monoflow loops. And from the basement monoflow loops they supply hot water to the five second floor cast iron rads.
Consumption is up this winter and am thinking that if the 007 circ were not doing its job the boiler would be cycling on a lot more. We have not had any no heat calls but the consumption is up.
1. - Does a circ slow down as it gets older?
From this chart I see how different models have different head and gpm.
2. - why is head pressure important if a pump impeller is sitting in supply side? I would guess that the over all lift is around 20 feet.

[Deleted User]

depending on where you are,

it's been much colder for longer periods than usual, hence, more fuel usage. i've burned much more wood this winter, and others have noticed this same 'phenomenon'

MikeyB

degree days

On Long Island from end of Oct 08 to now we've used 20% more oil but Degree Days only rose 4%. Has the temperature been colder in a way that eludes the DD calculation? It certainly felt a lot colder for longer than 4% more than the prior year.

Thanks,

David

[Deleted User]

it sure was colder longer here in

w by god va, and i def used 30% more wood. but adjusting for burning less oak, it may drop to 20%

allenh

this consumption is more than double last year. I am going to just replace the circ pump anyway.
138 CCF for 32 days for a three room apt is high. Insulation is blown in walls, apt above and below are heated.

[Deleted User]

just replace the circ pump anyway?

'From this chart I see how different models have different head and gpm. 2. - why is head pressure important if a pump impeller is sitting in supply side? I would guess that the over all lift is around 20 feet.' by saying that, and without my sounding offensive, your understanding of pumps is off, and since you didn't have any 'no heat' calls, you'll probably be wasting money on top of using more oil this past year. call a pro, bec replacing parts until you maybe get right is not the way to go

Uni R_2

Monoflo

As long as the rads are still being heated evenly the circ is doing its job. It doesn't really lift water 20' (the weight of the water coming back down is enough to pull the water up - like a ferris wheel), but what the circ does need to do is move enough water fast enough so that water is diverted through the heating branches.

If for some reason the flow through the monoflo system gets reduced (worn out impeller, piping changes, etc.), some of the more difficult branches to heat will either not heat up or not heat up consistently.

scrook_3

Circulator head & flow

2. - why is head pressure important if a pump impeller is sitting in supply side? I would guess that the over all lift is around 20 feet.

Lift has nothing to do with it, regardless of circulator location! Any lift up is offset by fall back down in the loop (much like what occurs in a siphon, the falling/discharging liquid lifts the rising supply liquid.

If you were tryng to fill a tank or vessel up high from a tank or vessel down low, then lift would matter.

In a closed loop such as a heating system pump head is required to overcome friction in the tubing. The longer the tubing; the smaller the tubing inside diameter; the greater the flow rate; the rougher the inside surface (a minor effect); and the greater the number of fittings, valves, bends, monoflow tees, etc. the greater the friction.

The circulator is selected to develop the desired flow rate at the head loss (friction) encountered. The circulator doesn't know where it is in the loop (unless inlet pressure's so low it cavitates, a very bad thing), only the pressure difference from its inlet to its outlet and the flow thru it.

Oil or gas fueled boiler? Condensing or non-condensing? Power burner or atmospheric draft? How old? What brand/model?

In any case it doesn't sound like your issue is a circulator issue, it might not even be a heating system issue at all, but could be a structure heat LOSS issue -- new drafts/air leaks, higher thermostat settings, colder winter, stuck bathroom exhaust fan, more people entering/exiting thru outside doors, etc., but it would not hurt to have the boiler/burner checked including combustion testing (CO2 or O2, drafts, stack temperature, fuel delivery pressures (oil pump or gas main), etc. in addition to control and limit settings, and temperature differentials across each of the two loops.

While you might get slight impeller wear over decades of use, (barring cavitation, which could destroy an impeller quite rapidly, and noisily, but that would be immediately evident on examination) you shouldn't see a significant change year to year. The speed of the circulator motor is dictated by the frequency of the AC power supplying it.

[Deleted User]

speed of the circulator motor is dictated by the freakuency

and when it's very infreakuent, the motor will stop <;-)

Mac_4

Circulators

Pumps do not lift and they do not suck (unless they fail), what they do do is create a presure difference. This presure difference occurs in a centrifugal pump when the fluid is moved from the suction(center of the impeller) to the outer edge of the impeller by centrifugal force. As the fluid moves away from the center of the impeller a lower presure occurs at the center of the impeller which the higher pressure fluid at the pump inlet(higher relative to the presure at the center of the impeller) then filles or at least keeps trying to fill while the pump runs.

clammy

system question

allen you stated that you are running 2 mono flow loops do both of these loops work off of 1 pump and are they zoned if so are they using zone valves ?if so you may be better off running each zone off a seperate pump .i would also check and make sure that these 2nd floor rads are air free and that your boilers water pressure is set hi enough for the height of your biulding.Are all the apartments being heated with raditors or is it a mix of raditors and baseboard if so you may have balancing issues and replacement of your circ will not help.if your boiler has been replaced recently maybe you should contact your installation company if not then when was the last time a qualifed hydronic heating guy has serviced your unit and system i may be cheaper to contact a pro to take a look and find the root of your promblem as others have stated changing your cicr may not fix your promblem .hope this helped peace and good luck clammy