HELP advice on: LIVE and NEUTRAL wires were connected wrong

[zappastix]

Hi

The request below was added to a post sent the other day that was thankfully answered, and I suspect
it has been missed, so I have sent as a 'new topic'

Basically, I was installing a direct replacement combi bolier circulating pump (Grundfos 15 - 50/60 130).

BUT the connector block on the new pump was faulty and I couldn't connect the live wire, so the pump
had to be returned.

The new pump arrived yesterday morning, within 24 hours of contacting them (they collected the faulty pump).

This REPLACEMENT SECOND NEW PUMP has come supplied with a long "suppression lead".

This long lead will make it easier to wire up the pump away from boiler but this throws up another question.


THIS IS WHAT I FORGOT TO MENTION ON ORIGINAL POST

I forgot to mention that when I went to disconnect the OLD pump I saw that the LIVE and NEUTRAL wires
were connected the wrong way round (live in neutral connector).

I was going to connect as the original pump was wired up i.e. the wrong way round but then I thought if I
do this and it blows the new pump I wouldn't be able to send the pump back as faulty.

I'm sure somewhere long ago that I read that swapping the 'neutral and live' around in certain
situations this is possible - but I didn't want to take the chance.


So I'd appreciate just a few more answers;

1)

Should I follow the WRONG way round wiring i.e. live to neutral connection and neutral to live
connection OR WIRE UP as it should be i.e. neutral to neutral etc?

2)

When I connect the long suppression lead to the main cable coming from the boiler do I just use a plastic
connector block and wrap some electrical tape around it?

3)

I have got some CHOC BLOCKS for Halogen lighting would this be ok to use to connect this long
suppression lead?

4)

Does anyone know what this suppression lead does?


If you want to read the original post it is under;

HELP WITH "SLOW BLOW FUSE" AND CONFUSING SITUATION
(posted Mon Sep 22 2014 12:12 pm)

Many thanks in advance.

Regards

Stephen

 

[Taylortwocities]

1)

Should I follow the WRONG way round wiring i.e. live to neutral connection and neutral to live
connection OR WIRE UP as it should be i.e. neutral to neutral etc?

NO. Use a multimeter or two probe test device to determine the correct polarity of the supply First.
Do not assume anything. Live must go to live, neutral to neutral.

2)

When I connect the long suppression lead to the main cable coming from the boiler do I just use a plastic
connector block and wrap some electrical tape around it?

3)

I have got some CHOC BLOCKS for Halogen lighting would this be ok to use to connect this long
suppression lead?

Chock blocks, on their own, are not acceptable. Electrical tape is hopeless as it comes unstuck after a while.
Also the leads needs train relief. If you are to use a choc block, then use a CHOC BOX as well.

Your lighting block should be rated at least for 5amps

4)

Does anyone know what this suppression lead does?

Sorry, I don't. Maybe something to do with reducing interference.
Somebody round here might, or ask on the plumbing forum.

 

[AdrianUK]

The new grundfos pumps have an electronic speed control built in. They are not just a simple winding & capacitor anymore.

I guess they have been having a few issues with the electronics getting upset by spikes/surges/noise on the mains & have decided to include a cable mounted suppression widget with each pump.

(We use a lot of these at work for a different purpose. They can be set to produce a constant head irrespective of the flow rate.... rather clever really)

I agree with TaylortwoCities that you should determine the correct polarity of the supply & wire accordingly, however, if the pump is connected with reverse polarity then nothing bad will happen - you will not blow up the new pump & it will not turn the wrong way.

 

[JohnW2]

The new grundfos pumps have an electronic speed control built in. They are not just a simple winding & capacitor anymore. ... I guess they have been having a few issues with the electronics getting upset by spikes/surges/noise on the mains & have decided to include a cable mounted suppression widget with each pump.

Interesting. Are you saying that there is something (a 'widget') on the end of the cable? The OP seemed to imply that it was just a cable that he was planning on connecting to something:

When I connect the long suppression lead to the main cable coming from the boiler do I just use a plastic connector block and wrap some electrical tape around it?

Kind Regards, John

 

[AdrianUK]

The new grundfos pumps have an electronic speed control built in. They are not just a simple winding & capacitor anymore. ... I guess they have been having a few issues with the electronics getting upset by spikes/surges/noise on the mains & have decided to include a cable mounted suppression widget with each pump.

Interesting. Are you saying that there is something (a 'widget') on the end of the cable? The OP seemed to imply that it was just a cable that he was planning on connecting to something:

When I connect the long suppression lead to the main cable coming from the boiler do I just use a plastic connector block and wrap some electrical tape around it?

Kind Regards, John

On the units I have seen, they supply about a 1m length of cable. Approx 20cm from one end is a moulded 'lozenge' about the size of a small egg. Talking to tech support reveals that this contains a suppression circuit ( I guess the standard inductor/capacitor filter). Gundfros recommend that only this lead is used to supply power to the pump

 

[JohnW2]

On the units I have seen, they supply about a 1m length of cable. Approx 20cm from one end is a moulded 'lozenge' about the size of a small egg. Talking to tech support reveals that this contains a suppression circuit ( I guess the standard inductor/capacitor filter). Gundfros recommend that this lead is used to supply power to the pump

Oh, I see - so it's just a 'supplied' power cable with a built in suppressor. Thanks.

Kind Regards, John

 

[zappastix]

Hi

First chance to get back and wrap this post up.

Just thought I'd add what the final outcome is going to be for those
that have followed other posts connected to this one - purely to help
anyone else who might find themselves in a similar situation.

I have included this post to the others posts connected.

I looked in to other boilers that others recommended.

I also checked other web sites with Boiler Installers recommendations
who on balance rated Worcester Bosch Greenstar **CDi Classic
as the boiler to go with.

Briefly a while back I did a flow rate test - 10 seconds gave me two litres.

So this equated to 12 litres per minute.

The boiler to be replaced was an Alpha 28CB.
The 12 litres per minute would have matched the Alpha.

I nearly went for Greenstar 29CDi Classic LPG - because that was the nearest
to the Alpha . . . . BUT I thought I best double check flow rate again.

This time I did a FULL 60 SECONDS and this resulted in exactly 14 litres per minute.

I really don't understand this discrepancy, (12 vs 14) but this is what it came out as.

So I phoned Worcester Bosch main help line - the woman didn't have a clue what I was asking
about and put me through to Technical dept.

The guy said the two boilers that I thought would be okay the
Greenstar 34CDi Classic OR Greenstar 38CDi Classic were both okay with 14/lpm

He said he'd go for the "38CDi" because it delivers 14 litres per minutes at 40 degrees.

And because it's not more than around £150 I'm going to go for the Greenstar 38CDi Classic LPG

I asked about an installer, he said if you use a local Gas Safe guy I wouldn't receive 7 years
(8 with fitted filter) parts & labour guarantee BUT I would get 5 years parts & labour guarantee.


For those interested Greenstar info;

Greenstar 34CDi Classic

Central heating output: 30kW
Domestic hot water flow rate: 14.3 litres per minute at 35 degree temperature rise
(provided adequate mains pressure is available)
Designed operational flow rate 12 litres per minutes at 40 degree temperature rise.


Greenstar 38CDi Classic

Central heating output: 30kW
Domestic hot water flow rate: 16.4 litres per minute at 35 degree temperature rise
(provided adequate mains pressure is available)
Designed operational flow rate 14 litres per minutes at 40 degree temperature rise.

Many thanks again - I couldn't have got here eventually without helpful snippets here and there.

Stephen

 

[ericmark]

1) Line and Neutral are both considered as live. However I have read some boilers can be damaged when they are reversed so in view of that I would insure they are correct way around.

2) I have experimented many times with flow rates. The big question is how is the flow rate controlled? On a modern boiler we normally have three devices exterior to the boiler which tell the boiler what to do. These are the thermostatic radiator valve the lock shield valve and the bypass valve.

The lock shield valve is important when starting up from cold, these when set correctly ensure every radiator get some hot water. But once the system is running they do very little. The TRV closes once that room is hot and once so many have closed the bypass valve opens and allowed hot water to circulate between it and the boiler.

The boilers software clearly changes make to make but it uses the return temperature of the water to adjust the boiler output. As either each radiator gets hot or the bypass opens the temperature of the return water increases. At first the boiler will reduce flame and once at minimum the boiler starts to cycle on and off. Often anti-cycle software monitors if the boiler is required at next cycle and increases or reduces the time between cycles.

Keeping the pump at a constant pressure helps this all work but it is the setting of the lock shield valves which ensures the boiler is able to heat the house quickly from cold. If the valves are left wide open then the house is heated radiator by radiator. The close radiator to boiler gets hot and returns hot water to boiler which turns off the boiler once the room gets hot the TRV closes and so hot water is no longer being returned and the next radiator in line starts to get hot. Clearly not quite as defined as that some heat will reach other radiators but instead of the boiler working flat out to heat the house it is running at reduced output due to those lock shield valves not being set.

The way the pipes are run clearly will also affect how it all works and having a modern boiler designed to use a bypass valve run with an older system where some radiators have not TRV will clearly up-set the control.

Listing boiler performance clearly does not help on it's own it's down to how well it has all been set up. To set up one measures temperature of water in and out of radiator with TRV wide open but this can be a problem in the summer as often they will not go wide open. There should be a cap which replaces the TRV head but often these are not left behind for user.

My parents employed a firm who specialised in fitting central heating. They send around 6 guys which means in two days whole lot is done and central heating running by end of day one.

One would expect since that is all they do they would be good at it. However when I came to look they had left 3 radiators without TRV fitted and had connected the power shower directly to mains input which is illegal. The shower I got corrected after a lot of work but still three radiators without TRV fitted.

As winter approached my mum complained her room was cold. I found every lock shield valve wide open. Simply adjusting valves and she got a warm room but lack of three TRV's was not helping.

Had it been a small firm I could have understood but this was a large firm.

I have developed over the years a distrust of plumbers. They may be gas safe but seems not water safe. Only the other day I caught one fitting a thermal plastic header tank to a system which included solid fuel heating. I was asked to wire up the immersion heater and realised wrong thermostat should be re-settable when solid fuel is used so if the water is overheated by the fire it will not stop the immersion heater working latter. So the header tank has to be OK with boiling water.

He was gas safe it was just he was not water safe.

 

[bernardgreen]

I have developed over the years a distrust of plumbers.

So have I ..

There are three that I know and trust but the rest ? ? ?

The one I trust most is against combi boilers. He sees them as a lazy plumber's short cut to easy money.

Make that four, a BG plumber advised against fitting a combi at my friend's house even though my friend had been convinced by local plumbers that a combi was the only sensible option. All he needed was a new boiler in a perfectly good central heating and stored hot water system.

 

[plugwash]

Make that four, a BG plumber advised against fitting a combi at my friend's house even though my friend had been convinced by local plumbers that a combi was the only sensible option. All he needed was a new boiler in a perfectly good central heating and stored hot water system.

I have a combi at my flat and I'm not especially impressed, bath filling takes ages and temperature varies with flow rate making it difficult to control temperature (especially as the bath is fitted with a bloody mixer tap so you can't individually see/feel the hot and cold streams)

My parents were also advised (and went with the advice) by BG to keep their stored hot water system with minor modifications* when having their boiler replaced.

*addition of a tank stat and changing the setup in the airing cupboard so hot water could be turned off while heating remained on.

 

[APHSLTD]

1) Line and Neutral are both considered as live. However I have read some boilers can be damaged when they are reversed so in view of that I would insure they are correct way around.

2) I have experimented many times with flow rates. The big question is how is the flow rate controlled? On a modern boiler we normally have three devices exterior to the boiler which tell the boiler what to do. These are the thermostatic radiator valve the lock shield valve and the bypass valve.

The lock shield valve is important when starting up from cold, these when set correctly ensure every radiator get some hot water. But once the system is running they do very little. The TRV closes once that room is hot and once so many have closed the bypass valve opens and allowed hot water to circulate between it and the boiler.

The boilers software clearly changes make to make but it uses the return temperature of the water to adjust the boiler output. As either each radiator gets hot or the bypass opens the temperature of the return water increases. At first the boiler will reduce flame and once at minimum the boiler starts to cycle on and off. Often anti-cycle software monitors if the boiler is required at next cycle and increases or reduces the time between cycles.

Keeping the pump at a constant pressure helps this all work but it is the setting of the lock shield valves which ensures the boiler is able to heat the house quickly from cold. If the valves are left wide open then the house is heated radiator by radiator. The close radiator to boiler gets hot and returns hot water to boiler which turns off the boiler once the room gets hot the TRV closes and so hot water is no longer being returned and the next radiator in line starts to get hot. Clearly not quite as defined as that some heat will reach other radiators but instead of the boiler working flat out to heat the house it is running at reduced output due to those lock shield valves not being set.

The way the pipes are run clearly will also affect how it all works and having a modern boiler designed to use a bypass valve run with an older system where some radiators have not TRV will clearly up-set the control.

Listing boiler performance clearly does not help on it's own it's down to how well it has all been set up. To set up one measures temperature of water in and out of radiator with TRV wide open but this can be a problem in the summer as often they will not go wide open. There should be a cap which replaces the TRV head but often these are not left behind for user.

My parents employed a firm who specialised in fitting central heating. They send around 6 guys which means in two days whole lot is done and central heating running by end of day one.

One would expect since that is all they do they would be good at it. However when I came to look they had left 3 radiators without TRV fitted and had connected the power shower directly to mains input which is illegal. The shower I got corrected after a lot of work but still three radiators without TRV fitted.

As winter approached my mum complained her room was cold. I found every lock shield valve wide open. Simply adjusting valves and she got a warm room but lack of three TRV's was not helping.

Had it been a small firm I could have understood but this was a large firm.

I have developed over the years a distrust of plumbers. They may be gas safe but seems not water safe. Only the other day I caught one fitting a thermal plastic header tank to a system which included solid fuel heating. I was asked to wire up the immersion heater and realised wrong thermostat should be re-settable when solid fuel is used so if the water is overheated by the fire it will not stop the immersion heater working latter. So the header tank has to be OK with boiling water.

He was gas safe it was just he was not water safe.

You may have a distrust of plumbers but you also have no idea of the function of lock shield valves or an automatic by-pass.

Thera are plastic cisterns that conform to the BS for solid fuel but most MI's ask for metal ones and they take presedence .

As a general rule 10% of the heating load should be fitted with lsv's as a heat sink for the boiler, the room in which the room stat is fitted should not have a TRV.

Just for info the reason for the suppressor lead on the Grundfoss pumps was due to a current surge on start up, this was enough to fuse the relay contacts on certain timers mainly Drayton. There were also issues with damage to alpha pcbs.

The suppressor is now built in to the pumps electronics so they no longer come with the lead supplied.