My first unfortunate isar encounter

[Riley]

Now I know many of you will laugh and say that any encounter with an Isar is unfortunate.

I just don't see many in my neck of the woods.

Problem I have is a circulation one DHW works absolutely fine. CH works only downstairs.

Diverter is making. pump has correct power and is rotating and there are no zones

I am leaning towards blockage but I just wondered if there were any weird and wonderful issues surrounding this problem on this model.

Any help as ever would be massively appreciated

matt

 

[Clint 1979]

I've been lucky enough not to have worked on one of these but only heard bad reports!
But sounds like the boiler side from what you describe is ok and like you say could be a blockage or air lock in the system! (unless the circulating pump is failing).
Silly question but have you tried closing all the rads downstairs to force the circulation upstairs? Might be worth a try.

Clint

 

[Riley]

Cheers Clint appreciated

yeah I did try the radiators off downstairs but absolutely no difference.

The owner is a friend of mine so I trust them not to try it on and they say that the heating was on for about three hours and then all of a sudden the system went as it is now

 

[Clint 1979]

Circulation???

Certainly sounds like a system blockage somewhere then and not the boiler.

Are the downstairs rads on drops? Strange how all rads upstairs are cold, you would expect at least one or two to show signs of warming up.
Must be air or as you say blockage, maybe drain down and add some cleaner to see if you can shift it?

Could shut downstairs rads again and check to see how the pump is running (slowing down, sticking)?

Sorry pal, hopefully someone on here may have come across it and can shed some light for you, couldn't possibly be all rads upstairs have TRV issues......could it? (that would be unfortunate)!

 

[tom609]

is it zoned ??

 

[diamondgas]

Does the boiler cycle quickly? Do you know your F&R temp diffs? The iso valves on these are poor and tend to sieze up, one could be closed down but not off? F&R temp diffs give you a better idea as to how well the system is circulating though? the boiler diverter may not be opening fully? Lots of possibilities to be honest... 🙂

 

[goz666]

Have changed three pumps this last month on Isar's. It's difficult to tell how good the pump is , but if it is the pump you will either have to upgrade to the new type pump, or find the old pump in stock somewhere and just change the pump head.

 

[bewsh]

Can't imagine it being a poor pump, usually if the pump is knackered, the upstairs rads are hot and downstairs cold?

 

[Leo21]

Sounds like a zone valve or an old non return valve left in from old installation. Is it the upstairs rads that are cold?

 

[Millsy 82]

How have you managed to avoid isars for 10 years!

I would be looking at the system too. A lot of these were thrown in.

 

[Riley]

Hi guys thanks all for your thoughts. Wasn't in till very late so just responding now.

no trvs anywhere so I've written off failure of all upstairs controls.
No zones it's only a small 2 bed house.
diff on f & r downstairs is perfect if you didn't know there was an upstairs you'd say heating was brilliant.
No rads on drops

im thinking blockage

 

[arran197]

Or a piping issue. Sounds strange that they don't get hot at all. It's like there's a valve somewhere that's been closed or a bypass that's open or something.

 

[Leo21]

Or a piping issue. Sounds strange that they don't get hot at all. It's like there's a valve somewhere that's been closed or a bypass that's open or something.

My thoughts as well.

 

[southcoastboile]

I like working on these as long as it's not replacing the main heat exchanger Or vessel I would never do that again. there fairly easy to fault find on. Although I did have one difficult one, display pcb causing water to fluctuate in temperature. God knows how you can diagnose that without looking at plate to plate etc first.
Sounds as if it is a blockage or pump issue. Someone messed with a bypass? That's one of those jobs you don't want from the sounds of it.

 

[Riley]

I like working on these as long as it's not replacing the main heat exchanger Or vessel I would never do that again. there fairly easy to fault find on. Although I did have one difficult one, display pcb causing water to fluctuate in temperature. God knows how you can diagnose that without looking at plate to plate etc first.
Sounds as if it is a blockage or pump issue. Someone messed with a bypass? That's one of those jobs you don't want from the sounds of it.

You are not wrong mate. I'm quite happy fault finding on Vaillant Baxi Glowworm and newer Ideals etc but these ones just give me a chill of terror as I've heard so many horror stories about em. I'm probably just being daft, but with your display pcb fault. That is just crazy. Must've been so satisfying when you got there though.

Ive nigh on convinced myself that this one is a piping issue now though. No idea why all of a sudden it's happened though nor am I any closer to actually finding said issue.

Ah well back to it tomorrow

 

[arran197]

I've found piping issues can suddenly crop up. I think it can be a collection of things, such as system starting to dirty, filters, pump starting to slow compared to when new, rad valves turned up or down, etc.

 

[Anton]

As someone mentioned in an earlier post. Look for an old anti-gravity valve on the heating flow to the first floor. Usually on a vertical pipe above where the old boiler was originally situated. They get blocked up with crud and stick shut. If you find one, take it out and take the guts out and fit it back in place. It's not needed with the new boiler.