Re-balanced - Radiators clicking

[RigidRaider]

Are you sure the clicking isn't caused by little blobs of solder jumping up and down in the vertical pipe to the valve?

 

[oldskoo1]

Thanks D_Hailsham i didn't realise the cold feed was isolated. I thought if cold water drawing into the cylinder was then circulated through the boiler but i assume its actually the hot water pumped through the coil which radiates heat into the surrounding tank?

I did think about the solder but i didn't think it was a good idea trying to isolate by fitting a magnet onto the pipe so close to the pump, i don't know the intended outcome or complications so didn't want to risk it.

1 thing is for sure

When the pump is only serving the DHW the pump noise is louder on the same pump speed (2).


I think i obviously need to sort this tiny droplet leak but i don't know how to balance the return temp from the HW. All i see is a black screw handle and i afaik this was a tank drain off which i obviously don't want to mess with.

 

[D_Hailsham]

I thought of cold water drawing into the cylinder was then circulated through the boiler but i assume its actually the hot water pumped through the coil which radiates heat into the surrounding tank?

The coil is like the element in a kettle, but hot water from the boiler passes through it and not electricity. In an case the boiler water has chemicals (inhibitors) in it, to prevent damage to the rads and the formation of sludge, which would not be conducive to personal hygiene and health

When the pump is only serving the DHW the pump noise is louder on the same pump speed (2).

That's why I suggested a proportional pressure setting as the pump will automatically reduce the pressure when only the cylinder is in circuit.

All i see is a black screw handle and i afaik this was a tank drain off which i obviously don't want to mess with.

There should be two more pipes entering the side of the cylinder, just to the left of the grey box in the pic. These are the connections to the coil. The left pipe is the return and, hopefully, has a gate valve which can be used to reduce the flow rate.

 

[oldskoo1]

Unfortunately there is no gate on the return just an aav on flow and manual air vent on return

And come to think of it there was loads of spilt solder dried on the old pump housing and pipes

If it is indeed solder what is the best course of action here? Would a magnet on the pipe be a bad idea so close to the pump?

Those magnetic filters I assume are for the iron oxide a system might produce?

 

[oldskoo1]

Ps regarding the proportional pressure setting, I'm afraid I don't know what this means? Are you suggesting I go down to speed 1? Or can the pump be configured to auto adjus?

 

[D_Hailsham]

Regarding the proportional pressure setting, I'm afraid I don't know what this means? Are you suggesting I go down to speed 1? Or can the pump be configured to auto adjust?

Here's how to set Proportional pressure:

The three [fixed] speeds [are] indicated by a steady green light.

Press the button for 5 seconds and the pump will change from fixed-speed operation to PP3.

This setting is indicated by a flashing green light.

Press the button quickly to go to PP2 and PP1.

If you press the button again it will revert to fixed speed 3.

Proportional pressure is a simplified version of Autoadapt. It changes the pump speed as the pressure in the system varies due to closing TRVs, shutting of a circuit at a motorized valve etc.

 

[oldskoo1]

Nice thank you I didn't see this mentioned in the manual

I assume a good start would be pp2 as I've been ruining ok on static speed 2

 

[D_Hailsham]

Sounds reasonable to me.

 

[oldskoo1]

Gave it a shot on pp2 then pp3 and doesn't look like it can maintain enough flow to keep the boiler happy as it keeps cycling after 5 mins

On the upside the pump has no noise almost sounds like it isn't on apart from the flashing green led.

I do get the occasional surge and noise though. Worried it could be a blockage somewhere but not sure where. All rads work well and water is inhibitor brown.

 

[D_Hailsham]

Gave it a shot on pp2 then pp3 and doesn't look like it can maintain enough flow to keep the boiler happy as it keeps cycling after 5 mins

May I suggest that you rebalance the system following my procedure?

The reason for saying this is that there is too big a spread in the amount the LS valves are open (¼ to 3 turns). I would expect it to be between an 1/8th and 1 turn. This because the flow through a radiator is only a fraction of the flow through the main pipe.

Let's assume you have 20 rads (makes maths easier ). Then, on average each rad only uses up 1/20th (5%) of the heat available. So the average flow through each rad has to be only 5% of the total flow. Part of the reduction in flow will happen when the pipe changes from the 22mm main flow to the 15mm feed to the rad, but the bulk of the reduction has to be caused by the LS valve.

What many plumbers/ heating engineers (call them what you like ) do not seem to understand is that the water is not pumped through the radiator. It travels though the rad because the pressure at the return side is lower than at the flow side, so the water naturally flows from the high pressure side to the low pressure side. The job of the pump is to keep the water flowing round the main circuit, which includes the last rad.

 

[oldskoo1]

Sorry for the delay I have been away

Thank you for the explanation, I wanted to check something before I rebalance. I thought that the reason for the boiker cutting out early in pp2/pp3 mode was due to the flow being too slow to move water out of the boiker quick enough.

Do you think the early cut off was due to the balancing meaning now the main flow is slower more heat is lost and the return is too cold causing cut out?

I don't want to set it to pp2 and find that even after rebalancing it's still cutting out early because the flow out of the boiler simply isn't quick enough?

 

[D_Hailsham]

I wanted to check something before I rebalance. I thought that the reason for the boiler cutting out early in pp2/pp3 mode was due to the flow being too slow to move water out of the boiler quick enough.

The boiler is putting more heat into the water than the rads are taking out. So the flow temperature rises quickly and the boiler stat turns the boiler off. Too cold a return will not cause this problem, but it could cause damage to the heat exchanger. However, that will not happen if the boiler return temp is over 55C.

The likely cause is that the boiler output is greater than the total rad output.

Does the problem occur when hot water and heating are both on?

I missed out three things from the balancing procedure:

a. It must be done with the pump on a fixed speed, not a PP setting.
b. It may be necessary to change the speed during balance to keep the boiler differential within acceptable limits.
c. It's more important that the differentials are consistent than that they are a set temperature. So if you find that you can't get them all to 11C, but you can to 9C or 12C or 13C, then that's acceptable.

 

[oldskoo1]

As a quick test I recorded the current lock shield positions and changed all the settings based in where the rads are in the loop. As a simple rule I out all the closest on 1/8 turn, going to 1/4 and 1/2 on larger ones and downstairs 1 turn on most big ones and 2/3 on smaller. And hall 3 turns.

I didn't measure it but it still runs good on pump speed 2 but the same happens when I use pp2/pp3. It simply cuts out the boiler after just 3 mins. But the pump doesn't even sound like its running it's very quiet. I don't know what that indicates.

I can only assume that pump speed for whatever reason is too slow to move the heat on those settings?

Boiler is on the ground floor and pump is on the middle floor of a 3 storey house. Maybe gravity and pipe resistance is at play here? Perhaps needs to push it up 8 metres

 

[D_Hailsham]

As a quick test I recorded the current lock shield positions and changed all the settings based in where the rads are in the loop. As a simple rule I out all the closest on 1/8 turn, going to 1/4 and 1/2 on larger ones and downstairs 1 turn on most big ones and 2/3 on smaller. And hall 3 turns.

That seems a good place to start, although I think I said that most LS valves are fully open at about 1½. So opening it to 3 turns is not necessary.

I didn't measure it but it still runs good on pump speed 2 but the same happens when I use pp2/pp3. It simply cuts out the boiler after just 3 mins. But the pump doesn't even sound like its running it's very quiet. I don't know what that indicates.

I can only assume that pump speed for whatever reason is too slow to move the heat on those settings?

If you are happy with the pump on fixed speed 2, then go with it.

The performance graphs for the PP settings do seem a bit strange.

Boiler is on the ground floor and pump is on the middle floor of a 3 storey house. Maybe gravity and pipe resistance is at play here? Perhaps needs to push it up 8 metres

The only thing which matters is the pipe resistance. The fact that it's a three storey house is irrelevant. Gravity plays no part.

 

[oldskoo1]

Thank you

At pump fixed speed 2 the boiler does seem happier. It will happily run for 30 mins without cycling and virtually no kettling.

The downside is plenty of crackling / gritty sounds and surging through the pump originally what i wanted to tackle.

I may go ahead and fit a magnetic filter on second opinion of a plumber when he sees what i have. When i was doing all the lock shields i noticed some had wept in the past and turned black and were gritty when i turned them with a wheel head. I'm not sure if this is linked and somehow that got into the system.

Shame the PP mode isn't suitable, the noise is brilliant.