circulatory pump in wrong direction?

JackieChan

I'm replacing an old oil boiler but just looking at the circ. pump it is sending water into the boiler.
I always thought that the pump should be sending water away from the boiler and into the house.
There is another circ. pump for the kitchen range if that makes a difference.
I'm just wondering why it would do that and if it makes an difference.

DoneDL

JackieChan, RTFM.
Manufacturers instructions will apply to every boiler for its warranty to be valid.

JackieChan

DoneDL wrote: »

JackieChan, RTFM.
Manufacturers instructions will apply to every boiler for its warranty to be valid.

RFTM? I'm guessing that's Read The F*ing Manual. Im not commissioning the boiler, just wondering why my old setup would be pumping in that direction-never noticed it previously.

DoneDL

Very commom for older boilers, Stanleys etc to be pumped on the return. If you read the boiler instructions you will find different diagrams for the boiler as regards pump position and it will vary between sealed and open systems.

JackieChan

DoneDL wrote: »

Very commom for older boilers, Stanleys etc to be pumped on the return. If you read the boiler instructions you will find different diagrams for the boiler as regards pump position and it will vary between sealed and open systems.

My query is on my oil boiler outside not on the one for boiler on my range.

DoneDL

A modern boiler will normally be pumped on the flow but it will be in the installation instructions and the pump is generally incorporated inside the casing for wiring the frost stat. Sorry JackieChan are you saying that the exterior boiler you are replacing has the pump on the return.

JackieChan

DoneDL wrote: »

A modern boiler will normally be pumped on the flow but it will be in the installation instructions and the pump is generally incorporated inside the casing for wiring the frost stat. Sorry JackieChan are you saying that the exterior boiler you are replacing has the pump on the return.

There is a pump independent of the boilers and it is on the return.Perhaps the pump needs to be placed on the flow pipe but just wondering could there be a valid reason for it to be done this way in the first place.

heinbloed

Well, modern standard household boilers have the pump usually at the return, not at the flow.
The observation made by the OP is normal: pump at the return, at the 'cold' side of the circuit.
This set-up reduces wear-and-tear and avoids the pump pumping steam (air) in case the boiler overheats.
Which could severly damage the entire central heating system.

A pump not only creates pressure, it creates suction as well. And water in the boiler being heated and sucked/underpressured at the same moment will reach it's boiling point (steam!) very quick. Which can be the case if the pump was installed at the flow, at the 'hot' side.

So the pump has to be placed at the return. With modern boilers in closed circuits.

heinbloed

We haven't seen the system, so if possible send in a picture, better a drawing.

Your DHW might be circulated in a separate circuit. Here the positioning of the pump (if drawing from a secondary heat exchanger) is not that important, the risk of steam creation would be much lower. Non-existent in a standard set-up.

Do you have a circulated DHW system installed ?

DGOBS

Heating design standards would always suggest the pump should be on the flow (believe t or not) and there are pros and cons for either

JackieChan

heinbloed wrote: »

We haven't seen the system, so if possible send in a picture, better a drawing.

Your DHW might be circulated in a separate circuit. Here the positioning of the pump (if drawing from a secondary heat exchanger) is not that important, the risk of steam creation would be much lower. Non-existent in a standard set-up.

Do you have a circulated DHW system installed ?

Hein, I'm afraid I'm a bit of a noob and not sure what you mean by DHW and secondary heat exchanger is a bit over my head. All I see is an outdoor boiler with the CP on the return pipe and just wanted to know if that was a mistake. I assumed (noobness again) that it would be on the flow....although your first post gives a valid reason for it to be done that way.

heinbloed

...not sure what you mean by DHW and secondary heat exchanger...

For longer distances between thermal source and tap circuits are installed. These circuits are pumped.
The advantage is that it won't take ages and plenty of water down the drain before the hot water arives at the tap.

The DHW circuits have their own pump, running independantly from the CH pump. And can run constantly or timed with a timer and/or a temperature sensor. So DHW is available at the tap on demand.

As said: these pumped (DHW-) circuits are installed with long runs, in situations where the heat source is far away from the tap.

JackieChan

I don't have a DHW circuit.

Just the oil boiler and a back boilder on my range.