no pumping away?

#1 plumba

Ive noticed that on the last few crown oil fired boilers ive installed, all the circulators are on the supplies?! i was always told to PUMP AWAY! Whats the deal, i really need to know for my own sake. i talked to the boss and he said well thats just how it goes with the new ones i guess. I know its a basic question but hasnt it been that way for a long time?

ALH_4

xt

As long as you pump away from the expansion tank, you are ok.

Kevin O. Pulver

numba

I'm with you, but I think the deal is that the new mod/con boilers have higher head heat exchangers. Therefore, the circ is put right there on the intake side of boiler where it can apply the most pressure. That's my understanding anyway. Kevin

Mike.C

I'm with Andrew

> I'm with you, but I think the deal is that the

> new mod/con boilers have higher head heat

> exchangers. Therefore, the circ is put right

> there on the intake side of boiler where it can

> apply the most pressure. That's my understanding

> anyway. Kevin



The idea is to pump away from the expansion tank to avoid pressure problems if i'm correct because the circulator has about a 5# pressure drop. The changing pressures from pump on and pump off can feed a water system too much pressure and have problems.
Please correct me if i'm wrong.

Mike.C

I'm with Andrew

> I'm with you, but I think the deal is that the

> new mod/con boilers have higher head heat

> exchangers. Therefore, the circ is put right

> there on the intake side of boiler where it can

> apply the most pressure. That's my understanding

> anyway. Kevin



The idea is to pump away from the expansion tank to avoid pressure problems if i'm correct because the circulator has about a 5# pressure drop. The changing pressures from pump on and pump off can feed a water system too much pressure and have problems.
Please correct me if i'm wrong.

Mike.C

I'm with Andrew

> I'm with you, but I think the deal is that the

> new mod/con boilers have higher head heat

> exchangers. Therefore, the circ is put right

> there on the intake side of boiler where it can

> apply the most pressure. That's my understanding

> anyway. Kevin



The idea is to pump away from the expansion tank to avoid pressure problems if i'm correct because the circulator has about a 5# pressure drop. The changing pressures from pump on and pump off can feed a water system too much pressure and have problems.
Please correct me if i'm wrong.

Mike.C

I'm with Andrew

The idea is to pump away from the expansion tank to avoid pressure problems if i'm correct because the circulator has about a 5# pressure drop. The changing pressures from pump on and pump off can feed a water system too much pressure and have problems.
Please correct me if i'm wrong.

Empire_2

Hi Guy's

Pumping away means away from the expansion tank period. Dan has a great book out called "Pumping Away" go figure. The book explains why pumps are put on the supply to the system in short to aid in air removal. That's not all, but I think everyone should own this book. Remember "Boyle's Law of perfect gasses"......Read this and It will make perfect sense.

Mike T.

Uni R_3

pumping away - modcons

Kevin, most modcons are piped on the secondary so it doesn't really matter for them. If they are restrictive like a Trinity, they are best if pumped into the HX to minimimze risk of cavitation among other things. If they are wide open like a Prestige, then the mfr can put the pump on the return side of the boiler, but either way it's kind of moot because the PONPC is on the primary circuit and the modcons are on the secondary.

The Vitodens is actually recommended to pump into the PONPC.

I hate to say it but I'm starting to get the feeling that pumping away probably made a huge difference with old style tanks and air scoops but doesn't really matter as much with diaphram tanks. My system is "pumping away" when it is valved to be P/S and "pumping into" the PONPC when it is valved to run direct as one big loop. It works fine either way.

Kevin O. Pulver

Hey Mike,

Yes, that's an excellent book, and I've read it several times. Ditto the rest of Dan's books. In one book, he made a big deal about why manufacturers always put the boiler circ on the return side, and the benefits of moving them to the supply side. Now, there seems to be a move to put them back on the return side of the low water content, higher pressure drop mod/cons. Of course, the PONPC principle still applies, but as Dan says, "the world changes." There are reasons the recommended circ placement is changing also, (in relation to the boiler, not in relation to PONPC)but I think there could be some possible confusion especially if you had paid attention to the book. Kevin

Kevin O. Pulver

Uni, I may be misunderstanding some terms

but my boilers are always in the primary loop, and the secondary comes off that with the proverbial, "closely spaced tees." (Or maybe a shiny new Caleffi hydraulic separator)Anyway, the corparate giant formerly known as Wirsbo always said in their initial CDAMS that the PONPC probably didn't make a difference in residential, but was more a factor in higher head commercial jobs. Of course, I piped them all the preferred way anyhow as I'm sure you did also. Kevin

ALH_4

away

The pressure gauge in the Vitodens jumps significantly when the pump comes on. The key is to keep the expansion tank connection between the pump inlet and the boiler outlet.

It is generally advisable to keep any flow restricting device on the discharge of a pump. Most mod/con's are flow restricting, in addition to being the point of heat addition. It seems to me that connecting the expansion tank at the low loss header and pumping from the LLH to the boiler is the best idea in order to minimize the possibility of vapor in the boiler heat exchanger. This way as long as the system pump is pumping away from the LLH, the expansion tank is directly connected to the suction side of the system pump also.

Empire_2

If you are talking P/S

I understand. Momma told me to pay attention and I usually think I do especially if I have all the facts.:-) I think we all are interested in new stuff, techniques and the like. Since he is using monoflo, I would think the pump discharge psi to be seen in the loop would be beneficial. Again just my opinion.

Mike T.:-)

Kevin O. Pulver

oops

Mike, I meant to say, "especially if ONE had paid attention to the book" (not if YOU had paid attention) Not implying you didn't pay attention. I agree with you that I like to have all the pressure downstream that my little circs can generate, but apparently, they want it pumping through the boiler HX first on these low mass mod cons. Kevin

McKern

Mike- Pumping into a monoflo?

Mike, are you saying that pump discharge gains would help pumping through the monoflo circuit because its very restrictive(a) or because it has higher velocity requirements(b)?

[Deleted User]

how about pumping both?

i just installed two, tandemed weil-mclain ultra 230s with 4 circs pumping away to four zones, while i have two circs pumping to, right at each boiler. the two, to, at the boilers was suggested by weil-mclain in order to ensure plenty of water for each boiler

Empire_2

Hi Uni R

First off I'd like to say, I don't know where I pulled in monoflo into the conversation. Might have been from another post.:-) To answer your Q: I am gonna go with A).:-) Each Mono T drops the available pressure a bit and your net loss at the end may become a problem. Delte P., I personally like to have all the pumps available out put go directly to the system so that there are less problems when using a properly sized pump.

Mike T.