bermuda 552 pump over run needed

[shorticus]

System; baxi bermuda 552, randall 3020p programmer, cylinder stat, Honeywell 3port y-plan, Honeywell room stat, air seperator (now plumbed in the correct way round). Boiler is powered direct from junction box as per Randall's/Danfoss's schematic.

Problem; When the room stat is satisfied it shuts down boiler and pump, excess heat in exchanger carries on heating the flow then woosh up it flies into the header tank steam and all. Apparently been happening for years. Very noisy but of course worst of all the header tank fills up with hot water.

Question; does anyone know a way I can create a pump over-run to dissipate this energy?

This is my girlfriends house and her twelve year old daughter sleeps below the header tank so I'm very keen to resolve the issue. Yes the system needs a power flush, I've spent the day raw water flushing and have now got all the rads working, got tons of muck out and have dosed the system with some leave in cleaner. Set the stat on the back boiler on low to try and lower system temperature.

Any help would be really appreciated.

Cheers Shorty.

 

[Billy Bob Bob]

this boiler does not need a pump over run, likely system design fault,sludge or over gassing or thermostat faulty(boiler)

 

[shorticus]

this boiler does not need a pump over run, likely system design fault,sludge or over gassing or thermostat faulty(boiler)

Hi Gasman.

System is definitely sludged up and I have very little faith in the original installation, the air seperator was installed the wrong way round which I corrected today. I also replaced all the valves in the airing cupboard as they were all furred up with limescale so I didn't fancy putting anything aggressive in the system untill I knew the valves would hold up. As said above I've put a mildish pre soak cleaner in to soften the muck up and will flush out again in a couple of days time. I'm hopefull that all this will sort it but if it doesn't do you know if there's a programmer that could give a pump over run, the Randall certainly can't?

Flame picture looks fine and she has it serviced every year, I ran out of time today but will check the gas rate when I'm next round, stat seems to respond to adjustment, what's the best way to test it to be sure?

 

[Billy Bob Bob]

its not a programmer that gives pump over run its a pcb,so in a 552 case n/a,if the stats responding more than likley its ok does sound like system issues

 

[shorticus]

yes I've checked the boiler manual and of course you're quite right there's no provision like modern boilers, I just wondered if there was a programmer that I'd not heard of that could do the same.

I'll check the gas rate and persevere with the clean, I'm probably gonna have to get tough with it and get a powerflush unit and some strong chemicals in there. If all else fails the missus quite fancies an open fire so I might fit her a nice new regular boiler, don't worry though it won't be an Ideal )

Thanks for your help Gasman, that's another beer I owe you!

 

[tamz]

Either give the system a good clean out or just turn the boiler stat down a bit.

 

[stevetheplumber]

as a temporary you could wire the pump to run continously

 

[shorticus]

Cheers guys, I've set the boiler stat to minimum and I was thinking about re-wiring the pump to run constant as a last resort, just spoke to the missus and it seems I might not have to though, apparently the system was quiet this morning. Perhaps the cleaner is starting to work!

Her kitchen rad is not warm at the botom so there's still work to be done, this rad was the most problematic and had stopped working altogether, I took it off and gave it a good flush out and gave the flow and returns a quick blast with mains water which dislodged loads of black cr*p. I think I'm really convinced now that the system needs a powerflush then full balance.

I'm also convinced that I should buy a powerflush unit. I was thinking Kamco but I've been told that Norstrom make good kit too, do you guys have a preference?

 

[washer]

I know that baxi have developed a part that you can wire in to the wiring centre to give a pump over run for the baxi bermuda, sorry I dont know the part number, but if you contact baxi they will definetly point you in the right direction, I have wired in a couple of these myself.

 

[shorticus]

I know that baxi have developed a part that you can wire in to the wiring centre to give a pump over run for the baxi bermuda, sorry I dont know the part number, but if you contact baxi they will definetly point you in the right direction, I have wired in a couple of these myself.

If the flushing doesn't cure it sounds like this could be the perfect answer. Do you have to give the 552 a permanent live? Presently the boiler is powered by a three core from the junction box in the airing cupboard upstairs, I'm guessing that I'd have to run extra cabling?

 

[washer]

Just dug out the invoice, baxi do a pump over run kit (which is basically a timer) for the 552, part number is 240340, wiring instructions included.

 

[shorticus]

Just dug out the invoice, baxi do a pump over run kit (which is basically a timer) for the 552, part number is 240340, wiring instructions included.

Many thanks Washer, I'll give them a bell later today
Shorty

 

[washer]

No probs, you dont have to run an extra cable to the boiler, the unit is just wired into the wiring centre.

 

[Deleted member 2053]

I might fit her a nice new regular boiler, don't worry though it won't be an Ideal

Why not? The new Logic + seems to really cut the mustard. I even deserted Vaillant and stuck one in my own house!

 

[Billy Bob Bob]

Why not? The new Logic + seems to really cut the mustard. I even deserted Vaillant and stuck one in my own house!

look in the yellow pages under m for masochist or m for mad

 

[stevetheplumber]

Might be cheaper to wire the pump thru another timeclock just set it 15mins after the other

 

[shorticus]

Thanks everyone for your input.
Seems like the cleansing and lowering of the boiler stat did the job although my girlfriend's daughter now misses the banging and gurgling alarm clock that used to live just above her head!! bless her.

Today I flushed out the cleaner and filthy water (took 3 flushes), dosed with inhibitor and balanced the rads, boiler gas rate at 11mbar giving just under 13kw which is about right for the size and type of house, set the stat at 1 so now have an LTHW temp of 70-75 degrees, when the room stat or cylinder stat interlocks the boiler and shuts down the pump there's a slight temp rise on the flow in the airing cupboard but no overboiling, sweet.

All rads are fully functional now and the house is toasty so Shorty scored some serious brownie points with the Missus!

Happy days )

 

[Billy Bob Bob]

bear in mind bermudas (551 and 552) have a design fault,the thermostat must be set on 3,on 1 it cant burn off its condensate(the hissing thats some times heard) and the combustion box rots away

 

[shorticus]

bear in mind bermudas (551 and 552) have a design fault,the thermostat must be set on 3,on 1 it cant burn off its condensate(the hissing thats some times heard) and the combustion box rots away

any idea what temperatures that the stat numbers represent Gasman? I've checked the manual and all it says is to set the stat at the required setting (which isn't much help)

I'm guessing that the stat might be less than accurate. I'm also thinking that as the system water is +70 degrees that the heat exchanger should be safely above POC dew point of 55 degrees, what are your thoughts?

 

[Billy Bob Bob]

dont know the exact settings,but have seen plenty of bermudas rot away because the stats set to low,on some of the pull off fire panels they recommend a minimum setting of 2

 

[tamz]

Setting 1 is approx 130ºF (54ºC) High is approx 180ºF (82ºC)

 

[shorticus]

cast and condensate don't mix for sure, I'll give Baxi technical a shout tomorrow see if they can give me some expected temperatures for the stat settings, I'm betting that this stat is giving quite high temps in relation to the numbers hence the overboiling at anything above 2.
LTHW should be around 70-80 degrees which is what I've got so I'm also betting that's usually achieved at a stat setting of around 3.

I'll let you know what they say, cheers for the head's up

 

[shorticus]

Setting 1 is approx 130ºF (54ºC) High is approx 180ºF (82ºC)

Well I think these figures would confirm my suspicions, the stat is inaccurate.
Also if the temp is usually 54 degrees at setting 1 the POC will condense thus rot the exchager

 

[tamz]

As Gasman said.
Keep it set to 2 minimum. 10ºF between the numbers.

 

[shorticus]

As Gasman said.
Keep it set to 2 minimum. 10ºF between the numbers.

I've tried setting 2, it overboils and fills the header tank up with scallding water.

The stat is working but its just inaccurate, as said before system water is 70 plus so there shouldn't be any condensate formation unless I'm missing something?