Gloworm ultracom 2 sxi problem with Myson mprt smart stat

[scoobydo123]

Delta is fine during initial burn even when at full bifta. It is fully re-piped all new radiators, 28mm on all runs reducing to 22mm around the valves then back to 28mm (due to having 2 bundles of 28mm going spare). Such a shame it behaves like this as I do like the MPRT. Will work out the flow through the system when I am next round there.

Does the fact that when it is starting up on the subsequent burn that d.40 drops even though 8kw is going in point to good flow? When do you think you will be seeing one again? (almost sounds like a song)

I see you are from Essex do you cover the RM7 area (Romford)?

 

[scoobydo123]

Internal bypass was way screwed a long way out. The screw as you probably know has a circlip on it. Am I correct that once the ciclip is up against the body of the assembley then it is fuly closed, If so then it was 6 1/4 turns out from this position thought it was supposed to be half a turn back from closed? Anyway tuned this in as far as it would go with the circlip in place and it still mis-behaves.

Have tested a bit more this morning and even with the MV parked open after the Stat goes in to TPI mode so full flow through the system when the Stat calls for heat again and the flow is down to 50 it comes on and still waits for 5 minutes before ramping, return was around 44 when the boiler came on.

Could it be that I have the lockshields wound in to much on the rads? The turn down ratio on the 30Sxi is not that great min is 8KW is this the issue however I would have thought that when it is firing (assuming at 8kw whilst it waits the 5 minutes) and there is no heat gain surely the logic would say get on and put some load on the system?

 

[picasso]

My number is in my profile if you want me take a look.

 

[scoobydo123]

By way of an update. I have monitored the behaviour of the boiler on a re fire whilst the stat is in proportional mode.

It fired when the temp was 42c, it rose to 50 (in 7 seconds) then within 1 minute this dropped to 43 with a return temp of 36. It then sat like this for 5 minutes with the flow only rising to 46 and flow to 38 before finally deciding to ramp up. Really not getting why it would behave like this.

 

[mickyg]

its not circulating sufficiently. its the same effect as a S53 on a vaillant 400 series.

 

[scoobydo123]

On max output circulation seems fine d.40 53c d.41 30c after 3 mins surely circulation is good?

Also whilst it is waiting the temp of d.40 actually reduces even though around 8kw is being put in this points to adequate circulation doesn't it?

 

[scoobydo123]

Mickyg not sure if you have read the whole thread but the boiler fires fine from cold but for some reason on subsequent burns it sits there waiting for 5 minutes even though it is nowhere near the target flow temp. It is 20c below target and have a delta of 7c. Once 5 mins is up it will happily fire to the value of 20c with no problems.

 

[scoobydo123]

Mickyg any more input to my lack of output

To clarify the boiler will fire 100% correctly (ie ramp up in a timely manner) apart from when the system is warm ie stat is in proportional range cycling boiler off/on.

 

[scoobydo123]

Bump for Mickyg

 

[scoobydo123]

Here is a video of it sitting on low gas 8kw on this model. Notice how there is not much heat gain despite a relatively high 8kw. Is this indicating good flow? Not sure if relevant but it does appear to gain a few degrees when first lit (notwithstanding the warm water that as come from the HEX when the system opens) but then even though 8kw is going in d.40 actually reduces. Unfortunately the boiler was not seeing the whole system i.e. some rooms TRV's would have been shut as tenants where not in and I did not have access to all rooms.

http://videobam.com/TCpiM

 

[matt1e]

Hi scooby, My take on this, (and I am not a Glow worm expert BTW) I don't think you are going to have much joy with this one (bar somehow reprogramming the boiler software) and It's pretty obvious why, The two devices (boiler and roomstat ) are not very complimentary due to the way they are designed to work
The trouble is that the boiler is designed around a different type of control system in mind which doesn't include TPI thermostats

Boiler from cold will fire on high gas rate from cold within 15 seconds or so. However subsequent fires sit on low gas for the same amount of time which happens to match the proportional time of the MPRT stat plus 3 seconds so only get a 5 second high gas burn!

Anyone got any ideas or do they all wait this long on subsequent burns?

yes, when there is a demand for heat from cold on its stat interface it will fire and and go on to high rate quickly, there's nothing wrong with the programming there!
Now the subsequent burn
as far as the boiler is concerned if the demand has ended then the room must be up to temp so allowing for a stat hysterisis of a degree and a half eg when there is a further demand for heat then why shift up immediately to high fire when ticking along on low will more efficient,better for the boiler and probably be good enough to satisfy the demand?
looking at the flow temp is irrelevant as depending on the ambient that particular flow temp may be enough, there's nothing really arguably wrong with the programming logic there either as as far as I'm aware glow worm don't promote TPI control and why should they as that particular boiler supports its own compensation controls which are far superior To the TPI stat you have fitted (this is not a dig by the way you have just been unlucky)
To get that system running the way I think you want it to then I think you have 3 choices mate

1)Talk glow worm into coming round and reprogramming the boiler to operate the way you want it....good luck with that!
2)Fit a different boiler that is more friendly to the stat
3)Fit a different stat that is more friendly to the boiler

This could be normal operation, check with S codes just in case and give glowworm a ring.

You might want to try these when you upgrade...

http://www.glow-worm.co.uk/products/controls/climaprosub2-sub-rf/

http://www.glow-worm.co.uk/products/controls/smart-wiring-centre/

http://www.glow-worm.co.uk/products/controls/new-wireless-outdoor-sensor/[/QUOTE]

I think I have to agree with Andy here
or this would be comparable to the Myson one but better as it will modulate the burner rather than switch it on/off

Matt

 

[scoobydo123]

Yes 100% agree that climapro will be the answer but with one caveat I am not sure if it offers a boost system/ override for when someone wants to override due to day of work etc. The boiler is installed in a HMO and I let people have access to it. Currently the MPRT is set for 17.5 low Mid 19.5 High 21. If someone is off work then they can press 1hr boost to go up to the high temp. If the climapro supports override I am not sure it it will go back to my normal economy setting? Have another HMO that was set to 28c for all time periods thanks to someone tampering!

I just find it hard to understand why it sits at low gas for search a long time (5mins)after the first burn when no appreciable heat gain has took place but do fully appreciate your comments that if the stat has stopped calling for heat why start high but I thought this was what the first 1 minute of the subsequent burn (at low) calculated what the system could take.

Will have a good read through the climapro instructions but they do seem very expensive given that I need to get the smart wiring centre as well.

GW are looking into it as they have reproduced the issue in there training suite. Vaillant did fix there issue with the 4xx series with a re-written software but this affected many more customers.

Other than this niggle I am impressed with its performance/price ratio.

Here is a video of the install at a higher gas rate hopefully we can see that flow through the boiler is ok?

http://videobam.com/Lsgue


To confirm the first video lasts exactly 5 minutes like this with nothing much going on which is exactly how long the MPRT will allow call for heat whilst in Tpi mode.

Didnt know about the climastat but this does not offer HW priority so unfortunately not of any use for me as I have to heat an unvented with the boiler.

Thanks very much for your input

 

[matt1e]

I just find it hard to understand why it sits at low gas for search a long time (5mins)after the first burn when no appreciable heat gain has took place
Didnt know about the climastat but this does not offer HW priority so unfortunately not of any use for me as I have to heat an unvented with the boiler.

as said it's all down to the programming logic
It doesn't know that no heat gain has taken place as there is no room temp sensor, it only presumes that since the stat has stopped calling after the first burn then the demand must have been satisfied (room up to temp)
of course because of the way the myson stat works this is not the case.
an option in the menu structure to disable or adjust the parameters of the restart low/high fire timer would be useful, whether they implement one in the future, who knows

Matt

 

[scoobydo123]

Yes this is how the converstion has gone with GW. However they really did not have much idea. If I knew what the logic was then I could perhaps put a heat dump in somewhere. They are supposed to be speaking with saunier duval about it.

My issue is that some people have quoted that it does not happen on their installations, and it has been blamed on my poor installation and lack of flow through the HEX. But I think my videos show good flow would you agree?