Biasi/Savio 428S - Pressure issue?

[steviebobs]

Hi again and apologies for posting new thread just after closing the last one, but need a little more advice.

You may recall I fitted a Honeywell 927 Wireless Programmer to this system and after various teathing probs all settled down nicely.

Previously I controlled room temps via the control on the boiler, set at quarter when not too cold, up to 3 quarters if weather turned cooler. Now of course I have the programmer set with various times and temps and just leave the boiler stat on full.

Now of course the boiler temp is higher than before and it seems to have introduced a pressure problem. I have no noticable leaks and no overflow via PRV, but in the morning, pressure has dropped to below operating point. I top up via loop for only seconds until middle light comes on and boiler fires. But after running for some time the 'high pressure' light comes on. No probs, boiler runs of course, but next morning back to low pressure light again.

I have measured the pressure at the EV and it is only half a bar. Is this simply my problem, a case of just 'pumping up' to a bar?

I know the system has to be de-pressurised when re-charging the EV, so was planning to close flow/return valves and opening drain on boiler to release pressure?

Any views welcome (again....)

SB

 

[steviebobs]

It is very unlike this forum not to be tempted into a reply....

Is there a problem with my question ?

Regards

SB

 

[Agile]

There were so many others over the holiday it sunk below the bottom of the page!

The EXV is failed or depressurised or feed to it is blocked.

Follow FAQ to repressurise it.

By the way you are not operating your boiler correctly. Turn the CH to where ever you would have had it before. Your new controller is not modulating the boiler, only turning it on/off.

Tony

 

[steviebobs]

Thanks Tony first bit makes perfect sense.

Im a bit confused with second comment though - even though I am sure it is dumb me just not understanding.

As far as I was aware, the Honeywell 'central unit' only has connection to the boiler by way of a pair of contacts, open or closed, based on command from roomstat. Contacts closed, boiler on, contacts open, boiler off. I set the CH boiler stat high to enable quick warm up but this I am missing some science somewhere...

Steve

 

[Agile]

All the controller is doing is to tell the boiler when heat is needed!

So you should set rad temp to whatever you had it set to before!

Tony

 

[DP]

steviebobs, My boiler too is set at max as temperature outside will soon be -8. Roomstats (I have two) are controlling the ambient temperature for the two zones.

There was a time when boiler were run at low boilerstat setting during summer and higher during winter. I just leave my boiler set at high and let the room thermostat do the controlling.

It was set to medium during summer to heat hot water to safe 55 degrees C. Come the winter, the stat was set to high to deliver hot water to rads that allowed the rads to radiate heat equal to the heat lost from the room. Hot water now heated to a temperature that could scald.

With full control system in place, I see no reason why the boiler cannot be run at high temperature. In fact, if weather compensators were fitted to a boiler, the boiler stat would be at max anyway, with controls then dictating what the actual setting was to be carried out electronically.

 

[steviebobs]

Thanks for those replies.

DP - I have independant controls on my combi boiler for CH and DHW temps, but thanks for the input.

Tony, I think I confused things earlier.

Before I fitted the roomstat I controlled house temp via boiler stat, the level dependant on weather temperature. With roomstat fitted and set at 21 in the lounge I was assuming that I could leave boiler stat on high, enabling 21 to be reached quicker, and the roomstat would then control.

For my benefit, can you explain the relationship between 'modulation' and the room stat demanding, or not demanding heat?

Regards

Steve

 

[Agile]

The only difference now is the room stat turns off the boiler when the ROOM temp is reached.

Its still more efficient, more comfortable and better for the boiler if you turn down the flow temp to the highest needed to adequately heat the room when its cold.

It may also be relevant to range rate the boiler down too but I dont remember if I told you how to do that on the phone.

Tony

 

[steviebobs]

Tony

Check your emails - I sent one to you at 13:00 today

Steve

 

[DP]

DP - I have independant controls on my combi boiler for CH and DHW temps, but thanks for the input.

I am familiar with the boiler. Example I qouted was to shed more light on reason why the CH stat gets altered with seasons unless a room thermostat is fitted,

 

[steviebobs]

THanks DP

I have always had the DHW stat on full - all seasons, and the CH stat variable dependant on season. But with the boiler being under the control of the roomstat now, I have taken the various elements of advice and heeded !

SB

 

[Agile]

The only difference now is the room stat turns off the boiler when the ROOM temp is reached.

Its still more efficient, more comfortable and better for the boiler if you turn down the flow temp to the highest needed to adequately heat the room when its cold.

It may also be relevant to range rate the boiler down too.

Tony

Thats my advice!

 

[steviebobs]

Thanks, as always, Tony.

Advice taken and heeded.

Steve

 

[steviebobs]

Gents

I realise it is a while since this thread was started, but I wanted to update.

If you recall at the outset, after fitting a new Honeywell Roomstat, I basically had a boiler that I pressured up in the morning, it ran all day absolutely fine, but in the morning after being off all night, it had depressurised to the point of inoperation. Hence my original question, ie was my increased boiler stat setting causing the problem.

Anyway, after advice from Tony and DP, I checked my Pressure Vessel pressure and it was half a bar. I followed the FAQ process to repressurise to one bar.

This was some days ago and I was still getting the original symptoms. I was certain I did not have a piping/rad leak, and also certain that my PRV wasnt leaking but to check the latter even further I disconnected the overflow pipe going outdoors and put a plastic basin directly below the PRV. This morning, my pressure was low again and I had a fair bit of water (2 pints?) in the basin. Ah, I thought, the PRV is leaking - until I heard a little drip !! The drip was actually coming from the drain tap on the boiler !!

I tried to tighten but got no perceptible movement BUT the drip has stopped.I am now assuming this has been my prob all along and although I got no perceptible movement on the tap, I am guessing I must have tightened it somewhat to stop the drip.

So, its on test for today. Interesting point, it does not appear to have leaked all day with heating on and pressure up, but leaked at night with heating off, gradually reducing pressure to the point of inoperation, which is how I found it each morning.

Sorry for long diatribe, but I know you guys like feedback

Regards Steve

 

[steviebobs]