Grant Combi-Boiler problem

Canucklehead

Hi.

Reading the manual and understanding how the boiler functions will help you determine if there is a fault with the boiler, controls or the end user.

GSR

fsa

Another update! Left for a few minutes (while psoting) had a look with my wife, switched it from ON to OFF/ONCE/TIMED then ON, motor ran for 12 seconds, then ignited as it should!

I really don't know what's going on with the system. After a few minutes it went off, but came back on twice in a row when cycled through the programmer steps above again. Once doing this the red LED on the "Receive" part of the Digistat SCR unit flashed a couple of times too.

I wish I understood exactly how the system has been set up and what it SHOULD do, but the boiler was serviced just before we moved in, so I never spoke to the engineer. As such we just inherited a fairly new system that had just been serviced that I thought would be working as it should! My dad was a plumber and I'm fairly used to oil CH systems (having had them for the past 12 years), but they've always been open systems with hot water tanks, so this sealed system without a tank is a new one on me!

Canucklehead

fsa wrote: »

Another development this morning - after providing some hot water, the system seems to have stopped completely, and when the programmer is switched to off for both HW & CH and then back onto ON, you hear the burner start and then stop almost immeiately. No lockout light is appearing on the burner and I checked the oil supply is fine.

This has happened before and was rectified by resetting the wireless remote and SCR units, but this doesn't seem to be working this time!

HELP!!!

From your OP.

This doesn't seem to have anything to do with the thermostat - which is a wireless Drayton Digistat module - which will still have the flame symbol (indicating it's requesting the heating to go on). when the heating goes off.

Conflicting statements.

Find and read all the instruction manuals you can find on the internet or in paper form in your home.

No one here can see your system so self help would be the logical way to go, don't you think?

How do you know the boiler was serviced? Have you seen the parts that were changed? Was there an invoice? Or did you take their word for it?

GSR.

zzzLazyDaisy

This might sound silly - but check that you don't have a dripping hot water tap. A hot water tap left with even the slightest drip is likely to knock the central heating off, because hot water takes priority.

I tell you this from personal experience

fsa

Canuklehead: I'm asking for advice - I'm not an idiot, I'm just not a heating engineer. Saying "Conflicting statements" is really NOT helpful, and they're also NOT conflicting statements - one was an initial assessment, another an updte on what was happening. I didn't say the wireless unit was the cause of the problem, but rather what happened in two isolated incidents.

I have looked at the manuals for these systems (thanks to diywhynot!), and they're some help, but not any more than I've stated. I am trying to help myself by going on this forum and asking those (hopefully) better experienced than myself for their advice, and your comments (such as they are) aren't really helpful. (Basically just "RTFM and help yourself")

If you read my posts, you'll see I say EXACTLY when the boiler was services, and yes of course we got a service report. If you don't want to help out, then please just don't post and let others who may have some insights and practical advice do so.

fsa

zzzLazyDaisy wrote: »

This might sound silly - but check that you don't have a dripping hot water tap. A hot water tap left with even the slightest drip is likely to knock the central heating off, because hot water takes priority.

I tell you this from personal experience

I'm prepared to try almost anything, so no practical suggestion is silly! Checked and no dripping taps (hot or cold!), so at least that's one thing I can eliminate - Thanks

diywhynot

Op: you've have given conflicting info. You've had problems in the past with the Digistat. By the way CH has years of practical advice on MSE but it is much easier to base advice on detailed (and correct) info from the Op(major problem on many of the threads which appear on this forum: frustrating for those who want to help).

Have you tried ringing the OFTEC who serviced the boiler for a bit of advice?

fsa

Perhaps I should describe other aspects of the problem.I'll describe boiler actions with different programmer functions - assume when I say "OFF", I mean the Programmer is set to "OFF", and when I say "ON", I'm also referring to the programmer state, and could equally be used with the programmer at "ONCE" or "TWICE" and in a period the timer is set to call for HW or CH.

• From OFF, if I put the HW ON, the boiler fires up for a time, then switches off - if the hot water tap is switched on, it fires up again (and we get nice hot water)
• From OFF, if I put the CH ON, the boiler fires up, and we very rapidly get a warm house (we have a small 19th century, 3 bedroomed mid-terraced cottage).
• From HW ON, if I put the CH ON, the boiler DOESN'T fire, and the house remains chilly. The way we remedy this is to switch the HW OFF, then put the CH ON (which also automatically switches the HW ON) - this fires the boiler and all is well.
• If the CH is ON for a few hours, we can notice it's got cold again and the radiators are not on. The programmer, however, has everything ON, and the thermostat has the flame symbol that shows it's calling for heat, but the boiler is not burning. Remedy is to swith to OFF, then cycle to ON (or teh ONCE/TWICE timed section)
• If the CH is ON and we run the HW, we get luke warm water at best.

So basically if the boiler is already on one function, it doesn't seem to acknowledge the other, and if it's on one function for a long time, it seems to forget it and be unresponsive. Reading the manuals to all the components hasn't really answered why this should be the case.

fsa

diywhynot wrote: »

Op: you've have given conflicting info. You've had problems in the past with the Digistat. By the way CH has years of practical advice on MSE but it is much easier to base advice on detailed (and correct) info from the Op(major problem on many of the threads which appear on this forum: frustrating for those who want to help).

Have you tried ringing the OFTEC who serviced the boiler for a bit of advice?

I wasn't saying that the Wireless thermostat was a problem, merely that resetting everything seemed to sort that particular instance. It could be something else we did or just the time involved in doing the wireless rest was the cause of the resolution. Hope that clarifies the apparently conflicting information.

Grateful for any help that anyone has - it doesn't seem to be a problem with an obvious, simple solution (like just the thermostat being off), so difficult to pin down.

spannerzone

I had issues with my Salus thermostat controller - the wireless thermostat sent commands back to the Salus control receiver but nothing happened from that point on so hot water worked ok but the CH refused to turn on. I replaced the Salus receiver (wired in) module and it cured the problem.

It sounds like you may be experiencing similar problems where the control switch isn't correctly changing between modes?

Just a guess of course.