Replacement radiator is colder at bottom than it is at top.

[D_Hailsham]

What I did not realize is that, when a Hot tap is on full and the diverter right over, the two heat exchangers are in series, so heat still travels through both HW hex and CH hex.

No they aren't in series, the diverter's like a changeover switch...

Have another look??

Done that!

The pump always pumps through the CH hex, even when the diverter is in HW position, so the primary water must flow through both CH hex and HW hex when the diverter is in HW position. If it didn't there would be no primary water circulation through the HW hex!

 

[Agile]

It is not a CH heat exchanger, its a primary HE used for all boiler functions.

Tony

 

[ChrisR]

Sorry DH I misread you but what you said was odd:

What I did not realize is that, when a Hot tap is on full and the diverter right over, the two heat exchangers are in series, so heat still travels through both HW hex and CH hex. Presumably the HW hex is capable of absorbing all 28kW produced by the boiler, so the CH hex does nothing.

Er there isn't a CH hex.
Obviously the water has to go through both hexs to heat the tap water.

There's a heat exchanger from gas to water = the primary hex
one from boiler water to tap water = the secondary, or plate, or dhw hex
one from boiler water to house, = the radiator system!

What isn't being understood is that a minimal flow on the HW tap will make the diverter go right over. It's a pressure device. As soon as the pressure is taken off the tap water side, the spring pushes the apple core.
There's a tiny "area" where slight pressure relief is balanced by the spring, but it wouldn't be easy to get it to stop partway even if you wanted to. As the tap warms up the flow changes so the pressure changes...etc.

That's why "open in the tap a small amount" isn't a diagnostc tool - you don't reallly know what's going on.

 

[bluey831]

I am in Perth.

It would be great if I could get someone on here who knows how to diagnose to fix the problem.

Better than the locals fixes.
fluff

Out of interest fluff - why do you think none of the local fixes can do it? My view is that - taking the 80/20 rule - probably 80% of all local professionals - be they engineers, plumbers, decorators etc - would do a decent job in that profession. The big fear for the customer is getting one of the 20%. I'm guessing this would be roughly the same for every area of the country in terms of ratio.

I am about to have an install done and am debating whether to get BG or hope I get a good local RGI. This thread has made me vere towards BG as I have an old system and an old house etc. My view will be that if BG does it - then I pay what they ask and they provide me with a suitable working system - no matter how often they have to call to it. A local RGI can only come out so many times before he is losing money.

As mentioned in a previous post, if I were in your position I would have Homeserve out to either fix or provide written evidence of their complete exoneration from the source of the problem. If at a later point you find the latter incorrect then you have a case - if not you will have a working system. Your situation is something that I definitely want to avoid - equally though, looking at purely from a laymans perspective, I think until you take definite action and go through a detailed process of elimination with an on the job professional, it might be ongoing for a time yet.

 

[D_Hailsham]

Er there isn't a CH hex.
Obviously the water has to go through both hexs to heat the tap water.

There's a heat exchanger from gas to water = the primary hex
one from boiler water to tap water = the secondary, or plate, or dhw hex
one from boiler water to house, = the radiator system!

Thanks for putting me right; I just wasn't thinking. It's so obvious.

There's a tiny "area" where slight pressure relief is balanced by the spring, but it wouldn't be easy to get it to stop partway even if you wanted to.

But Fluff managed to find a point at which the hot tap was running and the rads continued to warm up. The tap water got warm, so the HW hex was doing something.

 

[D_Hailsham]

My view is that - taking the 80/20 rule - probably 80% of all local professionals - be they engineers, plumbers, decorators etc - would do a decent job in that profession.

I would put it the other way round!

 

[fluff29]

Bluey831,

FYI I have contacted 4 local plumbers.

3 plumbers want to do a powerflush on microbore ranging from £400 - £500, without even looking at the system or being interested in what I have done to date.

1 plumber thinks pipework is ok and thinks we need a new boiler because the heat exchanger is gone. We only spoke to this plumber last week and I told him all about the various tests that had been done.

None of the 4 sets of plumbers are interested in checking any of the pipes on heat up, etc like the great bunch of guys on here have had me doing. I don't think all plumbers are like this but it is difficult to find the "good guys".

BTW, if it was so easy to get someone to be interested in doing all these tests for me, I would have done it by now. This has taken over my life at home and work.

Process of elimination:-

Either powerflush, no guarantee this will work, then cut back and renew pipework on all rads, starting at manifold.

or

Renew the boiler and hope this works.

No guarantees given that anything will work but both of these are expensive options and may not work.

Rant over.

All other plumber type guys,

I asked my boss to read the posts on here. He no longer thinks it is the diverter as the boiler is staying on longer and he agrees with Tamz.

 

[bluey831]

My view is that - taking the 80/20 rule - probably 80% of all local professionals - be they engineers, plumbers, decorators etc - would do a decent job in that profession.

I would put it the other way round!

Really? Not sure if you are being factitious or not!! I cant ever remember being knowingly ripped off and I have certainly never had the misfortune to come across any of the type featured in the TV programs etc. However, I do do as much research as possible if I am getting someone I don't know. There are varying degrees of a bad job of course.

Strangely enough, the Internet is one of the main sources for scams, cowboys etc. Fluff has said she would be happy to have someone from this forum come and do her system. While a lot of people are giving good sound advice to lay people like myself on here, there will be a percentage of cowboys on here also - either participating or lurking. I noticed on one building forum where some 'customers' wrote glowing references about a builder. I took the 'too good to be true' rule and wide berthed .....

My mate in Nigeria is still trying to put 258 million US Dollars into my bank account. As much as I would like the money, I feel I would be taking advantage of the nice man's generosity and, thus, have not got the heart to take his money. Therefore, I have not sent my bank account details for him to deposit all that lovely money.........

 

[DP]

But Fluff managed to find a point at which the hot tap was running and the rads continued to warm up. The tap water got warm, so the HW hex was doing something.

If the water is trickiling at the hot tap, now the load on the main heat exchanger is the poor flow through the radiators + what heat is passing through the plate to plate HE. Therefore, the burner stays alight longer.

 

[bluey831]

Bluey831,


BTW, if it was so easy to get someone to be interested in doing all these tests for me, I would have done it by now. This has taken over my life at home and work.

Process of elimination:-

Either powerflush, no guarantee this will work, then cut back and renew pipework on all rads, starting at manifold.

or

Renew the boiler and hope this works.

No guarantees given that anything will work but both of these are expensive options and may not work.

Rant over.
.

Fluff .... I so feel that I have been positively told off ... if not a good spanking. Yikes ....

The reason I am following this thread is that your problems are not dissimilar to mine. I have a conventional boiler and 11 rads. Some of the rads do not heat fully particularly the one in the living room. I have a BG Homecare contract and they have given me the usual 'have it flushed', 'strength of the boiler', 'the pipes could be kinked', etc etc.

I have not done anything about it for the last couple of years as most of the rads heat fine etc. This year I have decided to tackle it. My approach to this is:
My boiler is a 12kw or thereabouts - is 10 to 15 years old and somewhat inefficient. Therefore, I am going to need a new boiler at some point in next few years.

The system has never been flushed in my time here and there is sludge as far as I know. BG changed some valves and showed me the blackness of the water - though I know that does not necessarily mean sludge. The bottom of the radiators do not heat up like the top so that is indicative. Most all tell me there is no problem with powerflushing 10 mm pipes but there is a chance that some valves or rads might develop pinhole leaks due to their age - we think they are 30+ years.

My options:
a) do nothing and carry on with it as it is.
b) get an engineer in to do various tests to decipher the source of problems - but I would have to pay for this too as they aint gonna do it for nought.
c) get a new boiler with powerflush and magna filter etc. - which I am going to have to get at some point in any event.

If I opt for C then I will tell the installers the current problem and what I expect on completion - i.e. a working system with all rads heating up sufficiently etc.

So for me, it is not a case of having this done and the system not working. If that is the case it would be a breach of contract on the installers part and thus a whole different argument. However, I am not expecting this to be the case hence making as many enquiries as possible to ensure I am getting the right system and the right installer.

I do not want to fall out with my installer any more than I do with a Scottish woman ... I'm told they are a formidable force ....

 

[ChrisR]

Old heating systems are like old cars and old people.
They can have a lot wrong with them but still limp along.

More often than not there isn't just one thing that's showing signs of age, and they contribute, and interact.
So one guy suggests one thing, and if another says "NO, Rubbish!" you're left wondering, throw your hands up and get a new system!

 

[D_Hailsham]

If the water is trickling at the hot tap, now the load on the main heat exchanger is the poor flow through the radiators + what heat is passing through the plate to plate HE. Therefore, the burner stays alight longer.

I agree that the load on the main hex has increased, so the boiler will stay alight longer. But that does not prove that the problem is due to poor flow through the rads.

 

[bluey831]

Old heating systems are like old cars and old people.
They can have a lot wrong with them but still limp along.

More often than not there isn't just one thing that's showing signs of age, and they contribute, and interact.
So one guy suggests one thing, and if another says "NO, Rubbish!" you're left wondering, throw your hands up and get a new system!

I think that is my point. Our system is working and we can make do - but it is not working effectively and not giving us the comfort heat required for our house.

Regardless of what anyone says, if I did spend money on getting it working better - it would still be old and prone to further problems later. Therefore I have to make an informed choice about making better what I have got or getting a new system.

There has to be a cut off point in which spending on an old system is wise - unless of course I was intending to move house etc in the near future.

 

[vulcancontinental]

A few questions for bluey to help you make an informed choice; it's a bank holiday and I'm bored:

I am assuming you have microbore pipework.

1: Did the system work satisfactorily in the past and were you warm enough in the rooms you are not warm in now - this is the most pertinent question to ask anyone anytime in my opinion.

2: What make/model is your boiler?
3: Have you had to change the pump in the time you've lived there?
4: Is your boiler noisy?
5: Do the two pipes going into the radiator enter at the same end or one at each end of the radiator?
6: Have you ever had to change any of your radiators?
7: Have you got a room thermostat and a cylinder thermostat or a picture of the airing cupboard or pump?
8: What is the distance approximately from the pump, if it is in the airing cupboard, to the small tank in the loft (that's where most tanks are).
9: Do you have to bleed the radiators often? Is there a smell when you do?


If your radiators do contain sediment then they can be flushed individually and easily and cheaply and outside. This can be a DIY job, using chemicals is better and a flushing machine on each radiator better still. As far as I'm aware no flushing machine manufacturer suggests their machine will successfully flush and cleanse radiators through a microbore system.

A 30 year old radiator is an inert piece of steel. It was made of thicker steel back then and virgin steel as well. There are no moving parts to consider other than the valves.

I find old Servowarm radiators problematic, thin and prone to bursting if fitted to a pressurized system, other than that the rads will probably be Myson or Stelread possibly the old Potterton radiators; these were good, a picture might help.

The pipework is probably copper and will last for years. There are no moving parts to it other than the liquid passing through. If it's microbore it will have a thicker wall dimension than most 15 and 22mm pipework.

A modern boiler is crammed full of technology that can just as easily go wrong. In fact I argue often that there is far more chance of a modern boiler going wrong than an older one.

 

[bluey831]

A few questions for bluey to help you make an informed choice; it's a bank holiday and I'm bored:

I am assuming you have microbore pipework. Yes 10mm

1: Did the system work satisfactorily in the past and were you warm enough in the rooms you are not warm in now - Mostly but not in living room
2: What make/model is your boiler? Glowworm Ultimate
3: Have you had to change the pump in the time you've lived there? Yes
4: Is your boiler noisy? No
5: Do the two pipes going into the radiator enter at the same end or one at each end of the radiator? one at each end
6: Have you ever had to change any of your radiators? No
7: Have you got a room thermostat and a cylinder thermostat or a picture of the airing cupboard or pump? No room or cylinder Thermostat
8: What is the distance approximately from the pump, if it is in the airing cupboard, to the small tank in the loft (that's where most tanks are). Not sure but about 8 - 10 metres.
9: Do you have to bleed the radiators often? Is there a smell when you do? No

See answers above. Dont want to hog Fluffs thread with my issues - I dare not risk her wrath and I have a few threads on about it already. See ... //www.diynot.com/forums/viewtopic.php?t=237451