Problem with Vaillant 437 boiler

[jon26]

I have a problem with a Vaillant Ecotec 437. The boiler is connected to a large house one main header with a circuit feeding the ground floor rads, a circuit feeding the first and second floor rads and a flow and return feeding the underfloor heating. There is a pump on the GF circuit and a pump to serve the first and second floor circ, and a pump on the u/f heating manifold.

There seems to be a fault being shown on the boiler (I'm not exactly sure which fault code it was, could be F1), anyway the radiators are only getting luke warm, although a believe the rads at one point were nice and hot. If the boiler stat temp is turned right up to, say 70degC the boiler will run for a few seconds but then the temp will drop suddenly to say 40degC and dosent seem to rise back up again.

The pumps are working ok but the water isnt getting hot enough. The Vaillant guy has been out, he seemed to think the boiler was ok (but he didnt seem convincing). Could it be the way it has been piped up, or the position of the pumps perhaps, temp difference accross the header?

Has anyone come across this problem before on the Vaillant?

 

[gas4you]

I assume you mean a 438?

If you press the 'i' button when it is 'faulting', it doesn't read 'S53' does it?

What controls do you have on the system?

 

[jon26]

I assume you mean a 438?

If you press the 'i' button when it is 'faulting', it doesn't read 'S53' does it?

What controls do you have on the system?

Yes, sorry its the 438.

I have a feeling it is S53, I have heard this code mentioned by someone.

The controls are pretty standard, programmer with room stat to the GF and a room stat on the FF landing, U/F heating has its own stat in the one room which has u/f heating.

Does this help?

 

[Statia]

Do a search. Plenty to read about and answers to the S53 code on the forum.

 

[jon26]

Do a search. Plenty to read about and answers to the S53 code on the forum.

Cheers, some useful reading on there. Just one point, most of the forum was relating to a 28kW rated output and the benefits of perhaps turning it down to 24kW. This particular model is a 38kW heat output, can the output rating be reduced, this may solve the problem. If so, can this be done by pressing a few buttons on the display?

I have also heard about the ntc's and making sure they are fitted correctly (what are the ntc's?)

 

[gas4you]

Follow the MI's and get 'd0'' in the display. Press the 'i' button then reduce the output to what you want to try. Press and hold the 'i' button until the setting flashes to store it.

These boilers need a high flow rate through them at all times. On a standard system they would usually need the pump on the highest setting.

 

[jon26]

Follow the MI's and get 'd0'' in the display. Press the 'i' button then reduce the output to what you want to try. Press and hold the 'i' button until the setting flashes to store it.

These boilers need a high flow rate through them at all times. On a standard system they would usually need the pump on the highest setting.

I believe there are 15/60 pumps fitted to the system and they are all on their highest setting. By reducing the boiler heat load to say, 28kw or so, in what way is this likely to help get rid of the S53 code. Does it mean the boiler won't need to push out as much heat therefore increasing the flow rate through the boiler?

 

[jackthom]

S53 indicates there isn't enough water flowing through the boiler to carry away the heat so the water temperature is rising too rapidly.

Limiting the boiler to a lower maximum heat output by reducing the d0 value will make this less likely so the boiler may then get a chance to run long enough to produce a useful supply of hot water to the radiators.

 

[mickyg]

Although the S53 has been well documented on this site, mostly from people with oversized boilers and poor flow, your system differs in that you say you have a header. The problem could well lie here and really I think you need to be talking to your installer who spec'd the header.

 

[jon26]

Although the S53 has been well documented on this site, mostly from people with oversized boilers and poor flow, your system differs in that you say you have a header. The problem could well lie here and really I think you need to be talking to your installer who spec'd the header.

I shall try to reduce the heat load of the boiler and keep you posted on whether this works.
MickeyG, is there not a 'header' created on these types of system anyway, are you suggesting some kind of shunt pump may be required.

 

[mickyg]

I'm not suggesting anything as yet, just you mentioned having a header, with feeds from it. You didn't expand on this, but it just rung some bells with me. What exactly do you have? and yes if you have a Low Loss Header then a shunt pump might well be part of the answer, but I can't say from here, I'd just be guessing.

 

[mickyg]

is there not a 'header' created on these types of system

What type of systems? I think its picture time

 

[jon26]

is there not a 'header' created on these types of system

What type of systems? I think its picture time

The system has a 42mm. main pipe which the flow to the 2 no. CH zones and 1 no. HW zone are taken from. The returns all common together to feed back to the boiler. Im afraid I am unsure how to upload a picture.

Is a low loss header different to what I am refering to? Is this more of a purpose made main rind circuit need the boiler in which you can connect circs to / from. There are 3 no. pumps, each on the flow and returns from the header to the respective f&r's to the zones. I would have assumed the pumps even with only one active, would be enough to create adequate flow through the boiler.

Reducing the boiler load may help this.