S53 Code on Vaillant ECOTec plus 428- 28KW Boiler

[brett007]

Hi all

Please help I am beyond Desperate!!! Sorry for the long post but the more info I give hopefully the more you might be able to help. I moved into a 4 bedroom house last year Oct 07 & had the above boiler installed by a reliable plumber who wasn't corgi registered but had it signed off by a corgi registered plumber. I am generally quite good with DIY but this has me stumped!

Since the installation I have had continuous problems for 12 mths with the boiler. I have gone through 4 plumbers & have been in contact with Vaillant on numerous occasions, who told me to balance the system amongst other things. I am about to go through 1 marriage as well if I cant get this resolved. Below is the issue in detail.

I have an open vented system which is fitted in a "T" plan. I have 2 zone valves, 1 for hot water & 1 for heating. I have a Grundfoss 15-60 pump & a large cylinder - all in the upstairs bedroom & the Boiler downstairs in the garage. I have 14 RAD's, 8 upstairs & 6 downstairs all with TRV's. The room stat is downstairs in the entrance hall & the programmer unit is in the room upstairs with cylinder, pump etc

- When I fire up the central heating on its own via the programmer the system fires up, then goes into "high fire" & then shuts down with an S53 code which states: -
"Appliance is within the waiting period of the operation block function due to water shortage (VL-RL spread too big)"

- The only way to get the heating to work is to run the hot water as well, IE operate both zone valves.
- However by doing this the RAD's don't get that hot as the water is being split 2 ways. Only once the hot water has been running for awhile can I switch the hot water off on the programmer and then the heating will run.

In the afternoon when I get home I have programmed only the Heating to come on at 5pm, not the hot water. When I get in after 5pm the boiler is showing S53 and the RAD's are slightly luke warm.
- To resolve this I have to turn the Heating dial on the Boiler off, run the hot water via the programmer & then turn on the heating dial on the boiler and then run the heating via the programmer.
This most times gets the heating going but still get an S53 code at times during the evening.

- The system should run fine on its own without me having to do anything. The boiler is now out of Installer warranty (who wont return any of my calls anyway) but is still under the 2 yr Vaillant warranty.

Below is the series of events which lists what has been done to the system.

- Boiler installed Oct 07 and power flushed with a Magnatron (I think that's what he called it - the flusher with the magnets). (since then system been drained approx 8 times, water is crystal clear - no blocks/debris)
- Pump has been replaced 3 times with no debris found inside on any occasion
- Vaillant engineer came out, replaced the NTC's, & told me I had possible crossed pipe work. He dropped the output to 24KW. Called plumber back who confirmed piping not crossed - still not resolved.
- Another engineer came out & replaced the heat exchanger thinking it could be blocked - still not resolved.
- My plumber gave up, called another plumber - we together uncovered that the 1st Vaillant engineer had rewired the NTC's the wrong way round when he put the new ones in. We rewired correctly. They are positioned on the straight part of the pipe and not on the bends & are secure.
- Vaillant engineer came out again, changed the output back to 28KW.
- - I also kept telling everyone there was air getting in the system as I continually had to bleed the RAD's but none of them could figure it out. Called in another CORGI registered plumber to come sort this out. This CORGI plumber spotted it immediately, it was the tap on the positive side of the pump that was weeping and introducing air into the system. He has replaced this now - problem still not resolved.
- I have purged the system according to the manual and there is definately no air in the system now.

I also asked him to change the piping downstairs in D.Room (which was laid in a concrete floor) from 15mm - 22mm to increase flow as RAD not getting warm. He also tidied up the original Plumbers work to reduce the no. of bends in the pipe work. All long runs are now in 22mm with minimal no. of bends to improve flow.

- However to add to the problem, since then when heating was off and hot water on I am having reverse flow issues as well. I found the return pipe for the central heating to the bboilerin the garage was getting hot & the upstairs RAD's were getting warm. The water was eemanatingfrom the return from the cylinder to the boiler.
- To resolve this issue the plumber installed in a one way valve on the Heating Return just before where it joins with the cylinder return going back to the bboiler However whenever the heating is on the valve makes one hell of a noise as the sound ttravelsup the pipe work throughout the house, which is driving the wife mad on top of the heating not working.

- The current CORGI plumber has also installed a Manual Gate valve as the Bypass valve in the cupboard upstairs. It is connected to the flow from the boiler BEFORE the pump to the RETURN from the cylinder to the boiler AFTER the pump.

I still cant resolve the s53 issue

Please can someone help!! Everyone else has thrown the towel in on this one!!!

I have read Martin 2527's comments posted on Mon 6th Oct 08 - Vented System - Reverse Flow - I Think - but seems a little technical for me as don't quite understand but I think my problem is some how the same.

I look forward to any advice anyone has, thanks for your time!!!

 

[simond]

It sounds like;

There is nothing wrong with your boiler, because it manages the HW load adequately.

There is a restriction somewhere on the CH pipework.

I would suggest you get a radiator and some polyplumb, and try plumbing in just one rad after the MV and the pump temporarily to prove this to yourself.

Things we have found when encountering this sort of problem in the past include; sludged up anti-gravity valves in line left in the CH pipework, pipework blocked by Jablite in the F&E tank presumed put in when the house was repossessed.

 

[gas4you]

If you had reverse flow you would be getting a S96 code.

What pump have you got fitted?

Any pump on systems with these boilers fitted should always be set on maximum speed.

There have always been issues with poor flow through the 400 series and its predecessor the Ecomax Pro, it still has the same HE in the 400 series.

If the above is ok then I would have to agree with Simon, as the hW seems fine there h to be a flow problem on the heating side.

 

[Agile]

You clearly had a nupty installer as he did not fit an auto bypass valve.

Nor did he fit a gate valve on the HW to balance the flow to the cylinder against the heating.

I would say thats only to be expected if he cannot get CORGI registered and prefers to work illegally. It was also illegal for the CORGI to sign off someone elses work! Perhaps you are now realising that you would have been better off with a qualified person?

Some people are quite nasty and would tell the pair of them to pay an expert to sort it out or both get reported to CORGI.

A further nupty who fitted a gate valve instead of an auto bypass.

My recommendation is to fit the valve on the HW circuit so that you can adjust for good CH when the HW is being heated.

Then rebalance the heating circuit. A good boiler engineer would be able to work out the flow rate on the CH circuit from measuring the different temperature and the boiler power output.

You have not mentioned the heating load. It could be that the boiler is over rated for the heating load. Try reducing the boiler maximum output to equal the radiator output plus 2 kW for the cylinder.

Tony

 

[mickyg]

- The only way to get the heating to work is to run the hot water as well, IE operate both zone valves.
However by doing this the RAD's don't get that hot as the water is being split 2 ways.

The heating and hot water should be able to heat up adequately at the same time.

I am having reverse flow issues as well. I found the return pipe for the central heating to the bboilerin the garage was getting hot & the upstairs RAD's were getting warm. The water was eemanatingfrom the return from the cylinder to the boiler.
To resolve this issue the plumber installed in a one way valve on the Heating Return

How about getting your returns piped up correctly?

The current CORGI plumber has also installed a Manual Gate valve as the Bypass valve in the cupboard upstairs. It is connected to the flow from the boiler BEFORE the pump to the RETURN from the cylinder to the boiler AFTER the pump.

Are you saying the bypass is connected on the negative side of the pump

Normally you would pay for a qualifed heating engineer to install your boiler who would take care of any problems from start to finish.

 

[gas4you]

Nor did he fit a gate valve on the HW to balance the flow to the cylinder against the heating.

My recommendation is to fit the valve on the HW circuit so that you can adjust for good CH when the HW is being heated.

Wouldn't have one if the cylinder is the fast recovery type, nor should one be fitted if it this type of cylinder either.

 

[Agile]

I, and I think Mick above, would not agree with you Dave.

Avout once a month I come across a problem whichwould have been solvable if that had been provided.

I would go further and say that a pair of isolating valves should be provided so the cylinder could be changed without disturbing the CH circuit.

Tony

 

[snb]

The use of gate valves on cylinder returns is now not best practice as it renders cylinders unable to achieve the heat recovery times required as per part L.

That said if you use s plan configuration then the use of a gate valve is often the solution to getting all the rads hot when hot water heating is taking place.

But as the recovery time on most cylinders is only 15-20 mins then this the longest the heating system would be affected.

I would always advise that the hot water heating periods are set staggered to the heating period start to stop it being a problem.

 

[mickyg]

I always fit a balancing valve on the hw return, whether i use it or not is another matter

 

[gas4you]

Fast recovery cylinders rely on full flow through them to acheive their re-heat times as snb as stated.

Why fit one of these then stop it working to its max efficiency by fitting a valve to restrict the flow?

 

[Agile]

There is no "loss of efficiency" during reheating a cylinder. Its 100% efficient !

The Part L was aiming to eliminate boiler cycling which used to occur with non modulating boilers and undersized heating coils in the old cylinders. That problem no longer occurs with modern boilers and recent cylinders.

However, if the HW flow rate is too high the boiler differential will be too low to allow much condensing and the boiler efficiency will fall by 12%.

Tony

 

[gas4you]

The efficiency gain on a smaller fast recovery cylinder is measured by the speed it re-heats.

That is the whole point of fast recovery cylinders.

They are smaller than standard cylinders, so store less volume of heated water, but give the same or more usable hot water due to their ability to re-heat the contents of the cylinder quicker, as it is beingdrawn off.

If you fit a balancing valve to the pipe work you are intefering with their ability to perfom as intended for their smaller size.

It really has not got a lot to do with the efficiency as you are describing Tony. Thats another story.

 

[Agile]

I am only interested in energy efficiency, the amount of fuel used to heat a certain amount of water.

This OP has already said she has a LARGE cylinder. I interpret that as not being an undersized fast recovery cylinder. That enables it to be reheated efficiently in energy terms.

I see no point in undersizing a cylinder to the point where you have to compromise on boiler efficiency during reheat. I design for energy efficiency which some will have noticed when I advocate a full sized cylinder rather than the minimum you can get away with. 50 li + 50 li per person!

You only pay for the cylinder once at installation. You pay for heating it every day and year for 10-25 years or longer.

As for calling small cylinders "more efficient" thats only wording that a cylinder manufacturer would use as it has no basis in energy efficiency terms.

Tony

 

[brett007]

Hi Guys

Much appreciated for all your help. Sorry for my ignorance guys but most of what you have been saying has gone right over my head.

I will show the plumber what you guys have suggested and see what he says. I have fiddled with the timings on the programmer last night again and set the heating & hot water to come on at the same time.

I got home tonight to find the heating had kicked in with the Hot water & no S53 code. Was greatful to have heating but still means I have to run the hot water programme continuously just to get the heating going, which isnt ideal and not the most cost effective way of doing things.

In answer to some of the posts, sorry Simond what is Jablite & F&E Tank?There is brand new pipework between the Boiler & Cylinder so I know no other valves are fitted on this run.

Gas4you I have a Grundfoss 15-60 pump which is set at Max (speed3). One thing I did notice last night was whilst watching the MV operate (sad I know) I noticed that on start up with the HW MV the lever moves over and you can hear the valve open. However on start up of the CH MV I sort of hear the valve open but the lever never moves over to the open position. When you feel for play on the lever it moves all the way over but not of its own accord. I dont know if this has anything to do with it but I doubt it.

Agile sorry late last night, I forgot to mention the most recent plumber had fitted a manual gate valve on the HW Pipe between the HW MV & the cylinder. You are right, I will always go for a qualified individual in the future!! - Lesson Learnt. New to buying houses and using tradesman in the UK! In South Africa I would ask him "politely" to sort it out or I'll would introduce him to some friends I have in "low" places. Things do work differently here!!
Sorry I have no idea what the heating load is and cant seem to find it in the manuals, let alone know what the actual load is on the boiler. I will speak to the plumber about dropping the max output.

MickyG - as I said to Agile Lesson learnt re tradesman. The valve is on the Positive side of the pump (on the flow pipe from the Boiler to the pump (b4 the pump) & connected to the return pipe from the cylinder to the bolier on the negative side of the pump (after the pump). I dont know if this means anything to you????? I gather when you say negative side you mean after the pump??

SNB - if I stagger the Heating & HW periods this is when I get the S53 code.

Mickyg - what is a balancing valve??

Any more suggestions on solving the S53 code would be greatly appreciated as this is my main concern. The reverse flow I will worry about afterwards.

Thanks guys, much appreciated

 

[brett007]

Hi Dave & Tony

Below are the specs for the Cylinder: -
Make = Telford Cylinder
Size = 1500X450mm
Indirect grade 3
Nominal Capacity = 206 Lit
It has a green sticker that says "Part L compliant Product"

This OP has already said she has a LARGE cylinder

P.S. Tony - I see in your post above you said "she" I just wanted to let you know I am of the male persuasion

I hope this info will help you