What's wrong with this picture?

[nbtafelberg]

Yes that makes sense, I think at the moment its quite high up so I'm just seeing how we get on....

[Rick]

Generally speaking a central heating pump should be at the point of lowest pressure in the system. This avoids any areas of negative pressure which may cause air to be sucked in.

 

I would put the pump on the low level return to a boiler.

<{POST_SNAPBACK}>

 

The instructions which came with our Bolin stated that the pump should be fitted between the last rad and the stove.

 

The pump was the only bit that performed as expected when we turned our c/h on for the first time.

 

Richard

[nbtafelberg]

Hi Richard

 

Thanks for that, the heating is still not working.

 

:-(

 

Is that

 

STOVE ---- BOLIN PUMP --- RAD #3 --- RAD #2 --- RAD #1

 

or

 

STOVE ---- RAD #1 --- RAD #2 --- RAD #3 BOLIN PUMP

 

?

[John Orentas]

Paul.

 

Allow me to 'dip my oar in'.

 

If you have as described ; 1 stove, 3 rads, one pump. There's not many things that would stop it working. Make sure things comply with:

 

1. Circulation in the same direction as the natural convection, i.e. out at top of stove, out at bottom of rads.

 

2. Pump wired and connected correctly. If it is a centrifrugal type the ouput is the 'tangental' one and the direction of rotation must appropriate to that. The input pipe to the centre of the circle probably opposite the motor.

 

3. The pump should be low down in the circuit to ensure no air will stay trapped in it.

 

4. A header tank on the highest part of the circuit, note the connecting pipe should ideally be one inch or so in diameter, fairly straight and simple. Air must be able to bubble up through this pipe without assistance.

 

5. If there is another 'high point' in the circuit an air bleeding device should be located there too.

 

John Squeers

Edited December 4, 2004 by John Orentas

[DHutch]

yeah, and i still dont under stand where the photographed tank fits into the sytem?

 

- our system we have a stove, 3 rads, and a calrifyer on a "gravity feed" closed loop

[Rick]

Hi Richard

 

Thanks for that, the heating is still not working.

 

:-(

 

Is that

 

STOVE ---- BOLIN PUMP ---  RAD #3 --- RAD #2 --- RAD #1

 

or

 

STOVE ---- RAD #1 --- RAD #2 --- RAD #3 BOLIN PUMP

 

?

<{POST_SNAPBACK}>

 

The pump should be the last thing in the return pipe before the pipe connects to the boiler.

 

Remember that the pump is not as powerful as a domestic pump, someone once described it to me as annoying the water rather than circulating it. Our feed pipe from the boiler goes uphill immediately after the boiler for about 250 mm and then runs down hill to the first rad. At the apex of the incline I have an automatic air bleed valve and this is still chucking out the odd bit of air now and again. As I discovered it is asking a lot from the pump to cope with too many elbows especially if they are in the tappings to go to rads and in 15 mm to boot (but I don't want to talk about that).

 

Richard

[nbtafelberg]

Ok

 

The Boiler (in the picture) is a calorifier for hot water, it is plumbed into the same system as the heating.

 

LATEST THINGS - I have moved the PUMP now down to between the boiler and the first radiator, it was a job and a half! (which included me getting rather wet).

 

I've bled all the rads, the pump is working and i'm just waiting till the stove cools down before I bleed it.....

 

I have 22mm pipes.

 

You can ignore the aldi boiler because right now its not in the circuit.

 

Thanks for all your help so far I'll keep you informed as to what happens.

[nbtafelberg]

 

OK Have I got this right?

 

It's now between the Stove and the first RAD.

[Big COL]

Paul

 

If the pipe in your picture from the boiler is from the top connection on the stoves boiler then this looks ok, the inlet to the pump is under the motor and is connected to the flow from the stoves boiler, and the outlet from the pump which is at right angles to the motor is connected to the rads. In this configuration you are pumping the flow (just for information) this should work once you have all the air out of the system. My only comment on this configuration is that the pump is having to handle the hottest water in the system, but it will still work ok.

Edited December 5, 2004 by Big COL

[John Orentas]

The pipe to the left must be the oulet of the pump.

 

You said the pump was at the lowest part of the system !. It is connected to the top (output) of the stove. See my note about circulating as per natural convection, the top pipe of the stove you MUST make the output.

 

The photo indicates that the pump is at the top of the cicuit, it should be in the return.

 

Also air is likely to get trapped in the pump in that orientation. It couldn't be positioned worse.

 

John Squeers

Edited December 5, 2004 by John Orentas

[nbtafelberg]

Paul

 

If the pipe in your picture from the boiler is from the top connection on the stoves boiler then this looks ok, the inlet to the pump is under the motor and is connected to the flow from the stoves boiler, and the outlet from the pump which is at right angles to the motor is connected to the rads. In this configuration you are pumping the flow (just for information) this should work once you have all the air out of the system. My only comment on this configuration is that the pump is having to handle the hottest water in the system, but it will still work ok.

<{POST_SNAPBACK}>

 

Excellent Col, we'll get the stove going and give it a go I'm pretty sure the air is now out of the system after last night - I bled all the rads etc.

 

 

The pipe to the left must be the oulet of the pump.

 

You said the pump was at the lowest part of the system !.  It is connected to the top (output) of the stove.  See my note about circulating as per natural convection, the top pipe of the stove you MUST make the output.

 

The photo indicates that the pump is at the top of the cicuit, it should be in the return.

 

Also air is likely to get trapped in the pump in that orientation.  It couldn't be positioned worse.

 

John Squeers

<{POST_SNAPBACK}>

 

Ok - John because its a LOT of work to sort it out I'll try it as it is - the thing is that if I have to put it on the bottom pipe I have to add ANOTHER 4 elbow bits and that is going to be even more money out of my ever decreasing bank account LOL.

 

When I bought the boat by the way, this is where the pump was, however it was just joined by two bits of rubber pipe which meant that the flow of water was blocked, hence it only worked once in a blue moon.

[Big COL]

John

 

On a pumped system natural convection does not apply, as you normally come out of the boiler and drop to low level behind the boiler and then run flow and return at low level, the rads and cal are just tappings off a large loop of 22 MM pipe. the pump can go anywhere in that loop as long as it is configured to keep the water moving in the correct direction. The only downside to pumping the flow is that the pump has to handle the hottest water on the system, the advantage of having the pump on the return after all the rads is the water has cooled a little.

If you were converting a gravity system where the flow is running at high level then yes you are then right about natural convection and the pump needs to be at low level on the return.

[Rick]

If this doesn't work you could have air caught in the first elbow on the outlet side of the pump. I had this problem but i know a man who knows and he went straight to it. With the pump not running he cracked the joint and air and water came out. Problem solved.

 

Incidentally, the advice to put the pump in the return came from Bolin, but what do they know

 

Richard

Edited December 5, 2004 by Rick

[nbtafelberg]

Hi Richard

 

Yes - good advice, I will take it but I have to get to HOME BASE, I'm pretty sure you're right about the air lock. Only because the heat convects up to the pump and no further..... I'll do it this evening before we get the stove going and I get VERY hot water all over me :-)

 

The problem is that the bottom pipe I'll have to cut and add 4 elbow joints...oh dear...

Edited December 5, 2004 by clevett

[timboharticus]

Sorry, folks, I've just re-read my post above. It is wrong!!! (just testing)

 

The pump should ideally be at the point of HIGHEST pressure with it running which usually means at a low point before an item of resistance eg a boiler.

 

The idea is to maintain positive pressure throughout the circuit so that air cannot get sucked in.

[nbtafelberg]

Sorry, folks, I've just re-read my post above. It is wrong!!! (just testing)

 

The pump should ideally be at the point of HIGHEST pressure with it running which usually means at a low point before an item of resistance eg a boiler.

 

The idea is to maintain positive pressure throughout the circuit so that air cannot get sucked in.

<{POST_SNAPBACK}>

 

So am I right?

[Big COL]

Timbo

 

1 Why would the highest pressure be at the lowest point?

 

2 What positive resistance does a boiler cause bearing in mind that on most systems on boats the pump is overrated for the boiler performance and usually need slowing down.

 

3 On a closed system that has had the air evacuated from it how does the pump suck air in any opening in the system will leak water?.

[timboharticus]

When the pump is not running the point of highest pressure will be at the low point of the system due to the static head. There will be no resistance in the circuit because no fluid is flowing.

 

Once the pump is running it effectively "adds" pressure across itself but the various resistances in the circuit act as negative heads.

 

If all the pressures around the circuit are positive then the system will tend to leaking rather than sucking in air. If it was sucking in air , you would not see a leak.

 

If all the joints are 100% then no air should get in anyway, but it is much easier for air to get in than for water to get out through a tiny imperfection.

 

If the pump was in the wrong position and the flow rate was extremely high (unrealistic) then it would be possible for air to get in through the header tank.

 

I advise putting the pump at the low point in the boiler return before the boiler.

[nbtafelberg]

Right....

 

I've spent the last 4 days moving this pump around, its been High, Low, on the send and return and the rads are still cold.

 

I'm not jolly moving it again unless someone can give me a real reason why and what to do next.

 

Every move costs money because I have had to replace the old elbow joints and t-pieces.

 

Has anyone got a Bolin Pump manual? if its not too HUGE theres no chance it could be scanned and emailed?

[Big COL]

Paul

 

If you still have no heat in the rads then there is something else on the system causing a problem, either there is air trapped somewhere, or there is a problem with the pipe work where you bypassed the gas boiler, because as you describe the system set up it should work.

Its difficult to work out whats going on not having seen the pipe work so can we establish some basic facts and then go on from there

 

1 With the pump running and the stove running are you getting hot water on the return to the stove. ie the pipe that comes into the bottom of the stoves boiler.

 

2 If there is no hot water on the return how far is the hot water getting on the flow ie the top pipe out of the boiler.

 

Forget about the pump pumping air, this is a flooded system if there where any places that air could get in then it will leak water when the pump is not running. The pump is only there to move the water round a loop, air in the system is the most common cause, it gets trapped in places you would least expect I have had enough experience with this problem so know the problems well enough. Don't get disheartened you will get through this.

[nbtafelberg]

Hi Colin

 

LATEST

 

Got home took the Bleed valve off the back boiler and lo and behold the pipe was nearly empty so I filled it with water and put the bleeder back on.

 

I'm now running up the fire to see what happens, but there was a second where the hot water appears to have moved through the system. (the stove was coldish).

 

17:35 UPDATE: 1/2 hour later pipes and rads appear to be warming but very slowly so I've ramped up the stove to see what happens.

Edited December 6, 2004 by clevett

[Rick]

Has anyone got a Bolin Pump manual? if its not too HUGE theres no chance it could be scanned and emailed?

<{POST_SNAPBACK}>

 

I have one, a single sheet about A4, if you still want it I can scan and e-mail Wed evening.

 

Richard

[nbtafelberg]

Rick that would be useful mate :-) paul@ukconstruction.com I'll publish it on the web on my site....just if it might help anyone.

 

THANK YOU THANK YOU THANK YOU

 

17:56 RADS HOT - I'm Jumping up and down for joy! :-)

 

:-) :-) :-)

 

Especially BIG COL!

[Big COL]

Paul

 

 

OH YE OF LITTLE FAITH.

 

Great to see you have cracked it, you may still have to bleed the rads again as the system settles down. but at least its working.

[nbtafelberg]

Well you know mate,

 

Been doing this for 4 days with no results.