Hamworthy Wessex Modumax 200c

[diamondgas]

Hi folk,
Working on the above today, fault code E128 boiler locked out, code not in the mi. Re-set, ran through its parameters fga readings as per mi, gas pressure maintained, condensate running freely .According to the site maintenance they're re-setting it every morning. Its the bottom of 3 on the rig. I'm thinking fsd but reluctant to change it on a whim as it seems a tight thing to get removed (1st one I've worked on) ... Any ideas🙂?

 

[diamondgas]

I'm taking it that there aren't many commercial repair guy's frequenting just now? I've got the manufacturers number and will give them a call before I descend down into the basement ....

 

[diamondgas]

E128 = Flame drop out whilst on! flame rectification lost it's signal and I found the sensing probe wire conection loose around the electrode! Crimped together, pushed back on, job done!

Hopefully this may help others in the future...🙂

 

[Dotty]

Sorry DG, sorry sorry sorry! would've told you to look for that one, fairly common fault on them.

Not too bad to take apart, just unclip the wiring harnesses, undo 2 nuts and the whole lot comes out. Having a few issues with gas valves at the moment so you may come across that one! PM me if you want a copy of the mi's

 

[diamondgas]

Appreciate it croppie .... Just getting into commercial work these past couple of years... Really interesting ... 🙂

 

[diamondgas]

Okay gonna bring this back to life coz it came back in.

This a 3 way manifold of the same boiler. Imagine one on top of the other, 3 boilers one on top of the other! So, swapped problem burner assembly to middle section to see if it were associated with burner or PCB. Mid section faulted! Which indicated problem with burner section! So today changed glow coil igniter and flame sensor on mid section! The fan is somewhat more noiser than the other 2, bye the way! Any thoughts would be taken on board!

I'll keep you informed of the outcome ...

I'm aware you mentioned Gas valve 'croppie', what sort of issues have you experienced?

 

[Billy Bob Bob]

cant be of more help sorry Steve dont do commercial

 

[diamondgas]

Gas man i know mate .. the prices of parts are un-real man.

coz it's intermittent I went for cheapest first; £100 for the above and serious dosh beyond for gas valve etc. beauty about comercial is they tend to make sure if one goes down there's a back-up!

 

[SimonJohns]

Sorry I never seen this sooner. My current job is commercial breakdown enginnner and have quite a bit of experience with these boilers

First thing to check is your HSI. The resistance should be within 80ohm to 100ohm. This is more critical on other hamworthys but a good start

If your get the burner to light you'll be looking for a rectification signal of atleast 4 microamps. 8 is about the norm for a boiler that is due for a service

Depending on te age of the modumax you have you'll either have a burner tube with just slot holes cut in to it or you will have a burner covered in like a wire wool material. The wire wool looking one will require cleaning with water. Just give it a good flush thru. You'll be surprised at the debris that comes out. For the tube with the slots just a good brush with flue brushes and a quick wash

Flame probes is norm checks

Have a look inside and check you can see thru HE

Next combustion checks

The combustion values are critical. Not just on your co2 values. Bit how far your prob goes in. You probe needs to go in only 200mm and must be in the sampling point to the left of the burner. To get high and low fire hold the two button that have the spanner between them for about 8 seconds

It will the display 100% on the screen. Do your Fga and get your 9.3% co2 and then turn it down to 0% and get the same on low fire.

Any more help needed just contact


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[diamondgas]

Cheers, 'SimonJohns' .. just gettn into commercial repairs so it's all new for me ... your experience will be appreciated matey! I'll keep y'all informed if it comes back in ... The burner is the one with the wire wool look and the fault is totally intermittent. the maintenance guy's on site may notice it every other day! I fired it up over and over again without any issue, even let is cycle without fault, but take on board what you say regards the readings etc .. cheers!

 

[SimonJohns]

What you will prob find is that low fire is all to poop. And it may be losing flame due to under or over gassing. The smaller of the two Allan key adjustments on the gas valve will alter high fire and the larger of the two( under the big black cap) is for low fire. Just out of curi where is this boiler fitted ?


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[diamondgas]

It's situated in Newcastle Nuffield Hospital SimonJohn. Interesting you mention the low fire coz it goes off with quite a whooomfff!!! LOL

 

[SimonJohns]

If u mean it lights with quite a woomph. Then itll be a mixture of a possible over gassing and or burner blockage. With The HE causing more problems of heavily soiled. I look after the nuffield hospitals down here and the local bupa.
You got another commercial appliances u look after?

Btw another fault you may get on the wessex is flow issues. If you dont keep ontop of the strainers you can get an intermittent fault due to the temp rise being out of limits


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[diamondgas]

If u mean it lights with quite a woomph. Then itll be a mixture of a possible over gassing and or burner blockage. With The HE causing more problems of heavily soiled. I look after the nuffield hospitals down here and the local bupa.
You got another commercial appliances u look after?

Btw another fault you may get on the wessex is flow issues. If you dont keep ontop of the strainers you can get an intermittent fault due to the temp rise being out of limits


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I'm sub for a guy who's commericial. Simon ... Took on the repair side and am in at the deep end!

Regards other appliances, funny you should ask but there's a cpl dorchesters in need of seroius TLC!

 

[diamondgas]

Bye-the-way .. sat and passed commercial a year gone ... still a virgin regards repairs!!

 

[SimonJohns]

Depending on the Dorchester will depend on what u need to know. Alot of dr's are exactly the same as an andrews. But there are quite a few with burners on the side(riello). Just treat them as you would any other riello. O rings where the gas train connects to the burner tube are comman failure. Once commissioned CORRECT they are pretty trouble free. Just check turbulators (if flue has been installed corretly) and if you got the correx/ electrical anode. Check for good operation e.g. No red lights. And Descale depeneds on local knowledge. I can't get away with a good few years some times. But at most I do 2 years. Only because water is very soft down here and temps are kept low

If you ever have to order a pcb for any Hamworthy be very careful, had a big dispute with them over a sit pcb. Every boiler seems to have a slightly different setup and if you cannot identify all the parts that have been fitted to that boiler they may supply the "correct pcb" but the actual programming of the pcb is wrong. And made me look a total fool when I was actually in the right


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[diamondgas]

Thanks for the heads up Simon. There's two dorchesteres and one of them is off the scale regards CO! Awaiting an order to service it! Interesting that you mention the flue as in the past someone has disconnected the air intake flue and the main flue snakes it's way through the plant room in the basement up and out street level.
Thanks once again, I'll keep you informed...

 

[SimonJohns]

Has the dr got a riello burner?


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[diamondgas]

I'll let you know once we get back in, gonna need scafolding to work on it, they stand above head hight. lol

 

[Dotty]

Depending on the Dorchester will depend on what u need to know. Alot of dr's are exactly the same as an andrews. But there are quite a few with burners on the side(riello). Just treat them as you would any other riello. O rings where the gas train connects to the burner tube are comman failure. Once commissioned CORRECT they are pretty trouble free. Just check turbulators (if flue has been installed corretly) and if you got the correx/ electrical anode. Check for good operation e.g. No red lights. And Descale depeneds on local knowledge. I can't get away with a good few years some times. But at most I do 2 years. Only because water is very soft down here and temps are kept low

If you ever have to order a pcb for any Hamworthy be very careful, had a big dispute with them over a sit pcb. Every boiler seems to have a slightly different setup and if you cannot identify all the parts that have been fitted to that boiler they may supply the "correct pcb" but the actual programming of the pcb is wrong. And made me look a total fool when I was actually in the right


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Completely agree here. Of all the manufacturers we deal with hamworthy seem the most problematic. especially with part numbers.

As i said, my colleague fitted the 4th gas valve on a wessex 220m this morning, tried setting it up to give a burner pressure of 8.6mbr. could only get 4.8mbr maximum. another shouting match!

 

[SimonJohns]

Why did you set the burner pressure. I've only ever done these on combustion values with a gas rate to check. Being a fully modulating burner gas pressures I can't see why you would need to do that. And would't you need a differential manometer to get an approximation of the gas pressure


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[Billy Bob Bob]

Depending on the Dorchester will depend on what u need to know. Alot of dr's are exactly the same as an andrews. But there are quite a few with burners on the side(riello). Just treat them as you would any other riello. O rings where the gas train connects to the burner tube are comman failure. Once commissioned CORRECT they are pretty trouble free. Just check turbulators (if flue has been installed corretly) and if you got the correx/ electrical anode. Check for good operation e.g. No red lights. And Descale depeneds on local knowledge. I can't get away with a good few years some times. But at most I do 2 years. Only because water is very soft down here and temps are kept low

If you ever have to order a pcb for any Hamworthy be very careful, had a big dispute with them over a sit pcb. Every boiler seems to have a slightly different setup and if you cannot identify all the parts that have been fitted to that boiler they may supply the "correct pcb" but the actual programming of the pcb is wrong. And made me look a total fool when I was actually in the right


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talking of turbulators are they a mare to get out just like the domestic powermax? i wind a old cleaning brush around them and yank them out as they have normally collapsed

 

[SimonJohns]

Gas man

They usually not that bad. The flueways are bigger than the powermax and made of steel. So don't melt so easy. But the biggest problem is gettin to them. The flue is ment to be designed so that you can remove a good size section above the boiler to do any work. Such as, check annodes and flueways. When I worked in Bristol, the idea behind servicing was; make gas safe. And wait for cylinder to crack due to limescale


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[diamondgas]

Gas man

They usually not that bad. The flueways are bigger than the powermax and made of steel. So don't melt so easy. But the biggest problem is gettin to them. The flue is ment to be designed so that you can remove a good size section above the boiler to do any work. Such as, check annodes and flueways. When I worked in Bristol, the idea behind servicing was; make gas safe. And wait for cylinder to crack due to limescale


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Well still not got the go ahead as yet but what you've just said Simon bothers me. There's a boat load of gubbins above the cap of the unit! Ho-hum.... Will have to cross that bridge once we get the ok! Bye-the-way I know what you mean about the installations. There's a couple of Andrews heaters I've had to drain and alter pipework on just to get the burners out and seen steel posts erected in front of some burner trays that you know will never be removable! These past few years have been an eye opener!

Thanks lads :smile5:

 

[SimonJohns]

I'm pretty sure that from what U've said, that the heater has co through the roof, that the unit has a riello. When you look at the burner on the top right will be a chrome bolt and in the centre will be a flat head. That is the adjustment for the airdamper. I cant remember the exact setting off the top of my head but I'm sure it's about 3.5. And you will see your co come down. Thts if it is screwed in. Good luck. And anymore you get just send me a message


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