Air in CH system and hot water returning to FE tank via the cold feed

[Tiggy1955]

I have a problem with air being sucked into my CH system creating airlocks in the radiators. The water is flowing back into the FE tank via the cold feed pipe. I can feel warm water coming through the feed pipe back into the tank as the tank water level slowly get higher. I can hear the overflow gurgling in the FE tank.

The system is 20 years old but the Worcester Bosch boiler is only 9 years old. All has worked perfectly well. I did have the classic blockage where the cold feed meets the hot return but the clogged pipes have been cut out and replaced.

I have fitted a new pump and it is set to the lowest speed. All of the radiators have been bled many times and balanced.

So the heating is working fine except that I have this problem of the air displacing the water back to the FE tank. The water it getting back into the tank a quite a rate - I would say about 2 litres per hour. This means that the rads need to be bled constantly.

Any ideas? Could it be an problem with the boiler itself?

 

[Ric2013]

At 6l/m the old UPS 15/50 had around a 3m head and the UPS 15/60 around 3.6m head.

The very old Selectric UPS 15/50 and Super-Selectric 15/60 has 7 and 9 foot head, at 6l/min respectively, so a little less. (I say 'has' in the present tense because I know at least one that is still running.)

All the above are on speed 1.

I suppose it would be useful to plot a little chart showing various types of pump curve all on the same axes, so comparisons could be made.

Why am I still up?

 

[John.g]

At 6l/m the old UPS 15/50 had around a 3m head and the UPS 15/60 around 3.6m head.

The very old Selectric UPS 15/50 and Super-Selectric 15/60 has 7 and 9 foot head, at 6l/min respectively, so a little less. (I say 'has' in the present tense because I know at least one that is still running.)

All the above are on speed 1.

I suppose it would be useful to plot a little chart showing various types of pump curve all on the same axes, so comparisons could be made.

Why am I still up?

Will put together one (chart) later today, I will include my own old Salmson NYL 33 which I installed in Sept 2000 set to speed 2 and was still running perfectly and quietly when I replaced it last November with a Wilo Yonos Pico 1-6 last November.

 

[tonyt]

A bit off thread but I love this forum! It's so good to see people discussing issues using reasoned and evidenced facts supported by experience rather then slagging each other off.

 

[Ric2013]

A bit off thread but I love this forum! It's so good to see people discussing issues using reasoned and evidenced facts supported by experience rather then slagging each other off.

That's because I'm a left-leaning liberal **** as they say on Youtube when I'm trying to make a reasoned point.

 

[John.g]

Will put together one (chart) later today, I will include my own old Salmson NYL 33 which I installed in Sept 2000 set to speed 2 and was still running perfectly and quietly when I replaced it last November with a Wilo Yonos Pico 1-6 last November.

Here it is, I wouldn't care to be running a few of these on even fixed speed 1, especially the UPS 3 .

 

[Ric2013]

Here it is, I wouldn't care to be running a few of these on even fixed speed 1, especially the UPS 3 .

Doesn't work on Libreoffice. Thanks though.

 

[John.g]

Doesn't work on Libreoffice. Thanks though.

Here's a snapshot of it & also a Zipped word copy.

 

[Ric2013]

I take it that's the old UPS and not the very old one, but it looks wrong. The UPS 15-50 starts at a 0 flow at 3.5m exactly, so how are you getting 3.76? Have you yet another IOM, as that differs from my data?

 

[John.g]

I take it that's the old UPS and not the very old one, but it looks wrong. The UPS 15-50 starts at a 0 flow at 3.5m exactly, so how are you getting 3.76? Have you yet another IOM, as that differs from my data?

You posted

I take it that's the old UPS and not the very old one, but it looks wrong. The UPS 15-50 starts at a 0 flow at 3.5m exactly, so how are you getting 3.76? Have you yet another IOM, as that differs from my data?

I got it from one of your files above... "Selectric UPS Old Style" page 1 shows speed 1 curve starting at 3.75/3.76M ?.

 

[John.g]

At 6l/m the old UPS 15/50 had around a 3m head and the UPS 15/60 around 3.6m head.

The very old Selectric UPS 15/50 and Super-Selectric 15/60 has 7 and 9 foot head, at 6l/min respectively, so a little less. (I say 'has' in the present tense because I know at least one that is still running.)

All the above are on speed 1.

I suppose it would be useful to plot a little chart showing various types of pump curve all on the same axes, so comparisons could be made.

Why am I still up?

Can you post any links (charts etc) to a UPS 25-50 Selectric, power outputs 40W, 65W & 95W. (installed in a new build house in 2005/2006), still running.
Thanks.

 

[Ric2013]

You posted


I got it from one of your files above... "Selectric UPS Old Style" page 1 shows speed 1 curve starting at 3.75/3.76M ?.

Can you look at the chart on my file again and tell me what you see? I make it between 3.5 and 3.6 and would like to know if this is human or electronic error.
This is how it appears on my screen:

 

[doitmyself]

Can you look at the chart on my file again and tell me what you see? I make it between 3.5 and 3.6 and would like to know if this is human or electronic error.
This is how it appears on my screen:View attachment 36507

I have to agree with john.g. The speed 1 line crosses the y-axis at 3.75.

 

[John.g]

Can you look at the chart on my file again and tell me what you see? I make it between 3.5 and 3.6 and would like to know if this is human or electronic error.
This is how it appears on my screen:View attachment 36507

(Internet down for past few hours so couldn't relpy)

A bit confused as to why you ask human /electronic error as this I presume is a grundfos data sheet that you posted?, I just copied the data from it into my own spreadsheet, if you can post the proper chart I can incorporate that data in the spreadsheet and re post.

 

[Ric2013]

It's okay John. I'm not very good at reading data from a screen for some reason and I was reading the digits 3.5 against the 3.75 line.

So ignore my comments above.

 

[John.g]

It's okay John. I'm not very good at reading data from a screen for some reason and I was reading the digits 3.5 against the 3.75 line.

So ignore my comments above.

No problem, if you do come across any info on that 25-50 selectric with those power settings I would appreciate it. (#70)

 

[Ric2013]

Have you tried asking Grundfos? I think that's where I got the file for the VERY old Selectric pumps from. Rang them and asked for the curves IIRC.

 

[doitmyself]

Can you post any links (charts etc) to a UPS 25-50 Selectric, power outputs 40W, 65W & 95W. (installed in a new build house in 2005/2006), still running.
Thanks.

The curves are exactly the same as for the UPS 15-50 Selectric of the same vintage. The innards are the same, it's just the connections which are different.

 

[John.g]

The curves are exactly the same as for the UPS 15-50 Selectric of the same vintage. The innards are the same, it's just the connections which are different.

ref post#61
File "selectric UPS pumps old" shows the UPS 15-50 with power inputs of 35/45/50 watts. In "selectric very old" it shows the UPS 15-50 with power inputs of 40/65/100 watts with different speeds/curves, my query pump, a UPS 25-50 has power inputs of 40/65/95 so I will assume that the pump curves are similar to the latter one, above, its a 2005/2006 install. I wonder what was the time span period for the UPS 15-50 35/45/50 watts.

 

[doitmyself]

Here is the info you are looking for. The PC 9706 on pump data plate (see pic of the pump) shows that it was in production in 1997.

 

[John.g]

Here is the info you are looking for. The PC 9706 on pump data plate (see pic of the pump) shows that it was in production in 1997.

Thanks for that data.