Noisy return

[marshian]

Just looked at the instructions - not sure there is an orientation requirement on the Magnaclean but I will look carefully at the body when I'm home tonight

 

[John Carroll]

Are the vent and cold feed dedicated only as a vent and cold feed?, ie, there are no returns (or flows!) teed in anywhere to either of them.

My Vent from the boiler on the ground floor right up to the HW cylinder  (on the landing) have all the flows teed off from it.

Edited Thursday at 17:34 by John Carroll

[marshian]

4 hours ago, John Carroll said:

Are the vent and cold feed dedicated only as a vent and cold feed?, ie, there are no returns (or flows!) teed in anywhere to either of them.

My Vent from the boiler on the ground floor right up to the HW cylinder  (on the landing) have all the flows teed off from it.

 

Yes to both

 

The F&E tank is only feeding the CH Circuit - nothing is T'd off it - there is one isolation gate valve in the line but it's fully open

 

The vent for the CH circuit is vented to above the F&E tank

 

There is another vent from the HW cylinder that is vented to above the Cold Water Store Tank but there is no connection to it.

 

The pump is installed the correct way round and as I thought the magnaclean filter has no flow markings and according to the destructions can be installed either way up

 

The distance from the bottom T where the Vent is to the top of the pump gate valve is 58 cm it's as compact as it can be

 

From the pump to bottom of the F&E tank is exactly 3.4 M

 

The vent pipe is at it's highest point before it comes down to just above the surface of the header tank water is another 0.6 M

 

Huge apologies to @Little Clanger for the threadjacking

 

[John Carroll]

45 minutes ago, marshian said:

 

Yes to both

 

The F&E tank is only feeding the CH Circuit - nothing is T'd off it - there is one isolation gate valve in the line but it's fully open

 

 

Huge apologies to @Little Clanger for the threadjacking

 

 

The photo shows either a mid position valve or a diverter valve (with the adjustable spanner), why/how  is the F&E cistern only feeding the CH circuit, its teed into the pump inlet?, and whats the other pipe for?

Edited Thursday at 22:56 by John Carroll

[marshian]

1 hour ago, John Carroll said:

 

The photo shows either a mid position valve or a diverter valve (with the adjustable spanner), why/how  is the F&E cistern only feeding the CH circuit, its teed into the pump inlet?, and whats the other pipe for?

Oh that is such a long story I don't want to go there...........

 

Set up was a Y plan with a 3 position valve HW HW&CH and CH only

 

The whole system was controlled by a sunvic set up and when the 3 postion valve failed I converted to a drayton - however that was incompatible with the wiring centre and so an adjustable spanner was deployed to switch from HW to CH and

 

Nope I'll stop there.................

 

The pipe you want to know where it's going was to a manual vent - I've always had an issue with air in the system since we bought the place in 1991 it used to accumulate over time so I put a stupidly long leg of 15mm copper pipe up the side of the airing cupboard and just used to bleed it every month...................

[marshian]

22 minutes ago, marshian said:

The pipe you want to know where it's going was to a manual vent - I've always had an issue with air in the system since we bought the place in 1991 it used to accumulate over time so I put a stupidly long leg of 15mm copper pipe up the side of the airing cupboard and just used to bleed it every month...................

 

I guess this means whatever problem I have it's always been there - I just put something in that masked the issue

 

Now it's set up as X plan and has bottle vents on both HW and CH legs* they aren't as effective removing air as a 1.5 M length of 15mm copper right above the pump

 

*sighs

[John Carroll]

Can you post a photo of the pump&pipework as is now?

 

How far is  the boiler (elevation wise) below the pump?

 

You might do that glass test again but in a slightly different way which should prove whether the vent is continually drawing in air or not.

With the pump running at ~ 3M, only then immerse the vent end in the glass of water and see does the level remain the same.

22mm of copper pipe has a ID of 20.2mm so should have a capacity of 0.32L/M, a " 1 pint" glass say 0.5L, if all the water was sucked out of it on pump start up then the level in the vent must have dropped  by 1.6M, or 0.8MM if a 1/2 pint glass, I've read  that the level in a normal system falls by ~ 10mm in both the vent&cold feed with a running pump.

[marshian]

1 hour ago, John Carroll said:

Can you post a photo of the pump&pipework as is now?

 

How far is  the boiler (elevation wise) below the pump?

 

You might do that glass test again but in a slightly different way which should prove whether the vent is continually drawing in air or not.

With the pump running at ~ 3M, only then immerse the vent end in the glass of water and see does the level remain the same.

22mm of copper pipe has a ID of 20.2mm so should have a capacity of 0.32L/M, a " 1 pint" glass say 0.5L, if all the water was sucked out of it on pump start up then the level in the vent must have dropped  by 1.6M, or 0.8MM if a 1/2 pint glass, I've read  that the level in a normal system falls by ~ 10mm in both the vent&cold feed with a running pump.

Current set up

 

 

Filter, pump assembly is all same 

 

From pump

 

T to bypass valve to HW return

then T splits to go right for CH (NO zone valve) or goes left to HW (NC zone valve) coil in tank

 

Both CH and HW legs have bottle type air bleeds

 

Boiler is 1m below the pump 

 

I will try to do the new glass trick today 

 

Your calcs on volume of water in 22mm pipe assume that the height of the vent is also the length of the pipe but thats not the case the pipes go thro the ceiling of the airing cupboard and into the loft space - there they travel horizontally 3m along the loft before rising up to the F&E tank.

 

 

the tanks were relocated a while back because they made access to the loft space difficult 

[John Carroll]

Thats a nice circ pump, I've installed a few of them in my relations systems. They also show the flowrate in m3/hr, you might post this while running in CC2 (Fixed speed2) @ 3.0M on CH, you might expect to see ~ 0.7/0.8m3/hr, the pump also displays the power in watts (W), please post this as well,     How many rads??,

 

Not sure what you mean by the pipe calcs, for every meter change in level in a 22mm copper pipe, 0.32L of water has either to be added to it or removed from it?, IMO.

 

Do you leave the shut off caps on the two (automatic?) vents open allways and do you see or hear any air venting from them?, if you don't leave them open, why not?.

 

[marshian]

2 hours ago, John Carroll said:

Thats a nice circ pump, I've installed a few of them in my relations systems. They also show the flowrate in m3/hr, you might post this while running in CC2 (Fixed speed2) @ 3.0M on CH, you might expect to see ~ 0.7/0.8m3/hr, the pump also displays the power in watts (W), please post this as well,     How many rads??,

 

Not sure what you mean by the pipe calcs, for every meter change in level in a 22mm copper pipe, 0.32L of water has either to be added to it or removed from it?, IMO.

 

Do you leave the shut off caps on the two (automatic?) vents open allways and do you see or hear any air venting from them?, if you don't leave them open, why not?.

 

OK running out of time because we are going on holiday for two weeks but I’ll answer what I can

 

Pump speed 1

10-11 W in normal operation

Head is 1.8 m

flow rate is 0.7 m3/hr on HW and 0.6 m3/hr on CH ( it can get down to 0.3 m3/hr as room TRV’s shut down

 

Boiler flow temp 40 return temp 30 on pump speed 1

 

Most rads have a 9 to 10 deg drop between flow and return

 

Pump speed 2 

15-18 W in Normal operation

3.0 m head

Flow rate is 0.8 m3/hr on HW

and 0.7 m3/hr on CH (again it can get down to 0.3 m3/hr as rooms TRV’s shut down

 

Boiler flow temp 40 - return temp 34

 

most rads have a 6 to 7 deg drop between flow and return

 

House has 13 rads 

 

2 ladder towel rails (toilet and utility)

2 med size verticals (Bathrooms)

1 large vertical (kitchen)

4 T22 500 x 1200 (bed rooms)

2 T22 500 x 1400 ( Dining and main hallway)

1 T22 600 x 600 (front hall)

1 T33 700 x 1400 (living room)

 

Re pipe calcs (just saying whilst the height of the vent was as stated the length of the pipework to the vent is probably 7m from where it is below the pump to the outlet above the F&E tank. So there is a fair bit of water in the pipe)

 

Automatic air vents are open all the time but when air is introduced the aerated water tends to stay in the pipes - never hear them expelling air unless it’s a system refill then they hiss away a lot

 

if I shut the bottle vents for a day or so I’ll get a 1 sec hiss when re-opened so I know they work ok - I just think when the circuit gets a slug of air in it they aren’t very effective at getting it out due to flow of water in the circuit

 

I think that’s all of your questions answered

 

Better picture of the pump and pipe configuration below (with all the lagging almost complete it just looks like a sea of grey)

 

I’ve not lagged the bypass leg because I’m still trying to find a good compromise setting that doesn’t allow too much return when all rads call for heat but does allow a little flow when some TRV’s start to close

 

 

[John Carroll]

A boiler flowrate of 0.6m3/hr, 10LPM, with a dT of 10C gives a output of, 10*60*10/860, 6.98kw, with rad(s) outputs of ~ 21% (flow/return, 40C/30C) of their T50 rating. 

 

 I really can't see any reason for the system to be pulling in air,

the distance from the F&E cistern level to the pump is 3.7M and because the vent & cold feed are teed in before the pump suction then the pump discharge pressure will be 6.7M (@3.0M pump head) and irrespective of the pump head, the lowest pressure in any part of that system has to be 3.7M or greater. 

 

Try and do that glass test before you go on holiday (and enjoy),  IF the vent is pulling in air continuously then very very strange, the obvious one is wrong pump orientation but we know that the pump is pumping upwards.

Apart from that,  air ingress, over time, can occur through  pump gaskets or non barrier "plastic" pipework etc.

 

Edited Friday at 14:37 by John Carroll

[John Carroll]

This might be of interest as it shows the effect of the cold feed teed in both before and after the pump, I just calculated the pressures at 4 or 5 points in a system with a loop of pipe, but doesn't matter, the differential pressure through any system is still the pump head.

Point of No Pressure Change M Rev0.xlsx