Morco D61 wont fire up

[Ben Plant]

Hi All,

 

I've done a bit of searching and I know there's a few similar threads to this, but I can't quite find an answer to this, although I'm sure its not the first time it's happened.

 

I've just bought my boat, theres been a lot of "CSI" style working out why stuff is where it is, or hooked up like that, etc, etc.

 

I purchased a 2nd hand morco d61b with flue which I was assured worked. It was installed at the marina I'm in, by competent and qualified (and very good blokes) engineers.

 

The gas supply was uprated from 1/4" to 3/8" as previously the only gas supply was to a 2 burner hob. The gas supply is now 3/8" up to the morco, then the previously fitted 1/4" to the hob and a SMEV oven.

 

The water supply is via a shurco pump which is not brand new but is now working consistently. At the hot tap in the sink, I can measure a flow rate of 5l/min through the boiler.

 

So, the 2nd hand boiler was fitted, the pilot light worked fine, but the gas field would not light. We replaced the diaphragm in the morco as there had been a small leak, and checked the little pin could move freely. Still the same problem.

 

We decided that there must be a problem with the boiler so I bought a new one, fitted it, same problem.

 

I reckon it has to be either low gas, low water or both. (or if I'm very unlucky and the new boiler is faulty)

 

I think I should:

1: get the yard to measure the gas flow.

If thats low maybe try a new regulator. if not:

 

2: try a new pump. If that doesnt work:

 

3: try a new pump and a new regulator, in case its a combination of both.

 

I'd really appreciate it if anyone can let me know if I'm going down the right route in my diagnosis, or missing anything obvious.

 

Thanks in advance,

 

Cheers,

 

Ben

Edited September 19, 2013 by Ben Plant

[MoominPapa]

Are you sure the water inlet and outlet are the right way round on the Morco? In through the control valve, out from the heat exchanger.

 

Is there the possibility of another path for the water to get from the pump to the hot tap, bypassing the Morco? A calorifier, for instance.

 

MP.

[Captain Zim]

Is the water pressure high enough? When I had a similar problem with a morco I had to uprate the water pump. Can't remember minimum pressure off the top of my head but it's in the morco manual.

[smileypete]

Normally a 10lpm pump should do, do you get 10lpm 'open flow' from the cold tap? Maybe worth a try with just the heater connected to a water standpipe.

 

cheers, Pete.

~smpt~

Edited September 21, 2013 by smileypete

[Richard10002]

 

Is there the possibility of another path for the water to get from the pump to the hot tap, bypassing the Morco? A calorifier, for instance.

 

MP.

I had that with my Rinnai. Hot water could also get to the shower tap from the Truma water heater, so not enough pressure through the Rinnai to press the pin and fire it up.

 

Rejigged things so all water has to pass through the Rinnai to get to the shower hot tap, and it fires up every time.

[MtB]

I agree. The water flow rate through the Morce is too low, or reversed.

 

To pin this down you can remove the 'water section' and push up the pin on the gas valve to satisfy yourself the gas parts work. The boiler should light if you do this. If it does, this proves the diaphragm is not excercising and you have a water section malfunction.

 

MtB

[pelicanafloat]

Normally a 10lpm pump should do, do you get 10lpm 'open flow' from the cold tap? Maybe worth a try with just the heater connected to a water standpipe.

 

cheers, Pete.

~smpt~

I would do exactly that. Run a hose from the marina standpipe and feed it directly to the heater. Assuming of course that the standpipe has a decent pressure. If the boiler starts up then you know to fit a higher rated water pump. More importantly, you also know that probably the first boiler was ok.

 

I'm curious. The heater is 11kwatt rated, quite powerful, yet only 3/8 (8mm) supply to it. The competent fitters would/should have done a commissioning pressure test pressure test on both services..... so what were the figures? (Normally, these figures placed in the relevant boxes in the certification)

 

I'd do the water connection, and if this fails, then I'd talk to the manufacturer techies explaining the problem. They normally very helpful.

[Richard10002]

I had that with my Rinnai. Hot water could also get to the shower tap from the Truma water heater, so not enough pressure through the Rinnai to press the pin and fire it up.

Rejigged things so all water has to pass through the Rinnai to get to the shower hot tap, and it fires up every time.

Ben: What was supplying hot water before you fitted the gas water heater - are you certain you have removed the route from this to the hot taps?

[Ben Plant]

Hey Everybody,

 

Thanks very much for all the help and advice, I'll try and do my bit to respond to the questions.

 

I tested boiler 2 by connecting my 11 l/min Jabsco pump straight to it with a length of hose and it fired up straightaway. I swapped back to boiler number 1 and it also worked. Luckily, the top chaps at the marina let me return the 2nd boiler for a refund. (Thankyou).

 

On plumbing back in to the system the boiler wouldn't work so I guessed there must be either a leak or something else leading to low pressure on the part of the system I could not see, behind the tiled walls of the bathroom. Rather than track it down I managed to run a fresh length of hose from the shower taps straight back to the boiler/pump and everything was good as gold.

 

Before having a Morco, Heron had a single coil calorifier which wouldn't have suited my lifestyle. Wake up, quick shower, off to work. Somewhere in the old plumbing to the shower/calorifier was the leak/pressure loss.

 

Thanks again for all the help, for anyone else facing similar problems, the most valuable help for me was the idea of breaking the problem down into its component parts, (i.e. Does your hob work, OK you have gas, next: Plug the boiler into a good water source and see if it works, etc).

 

Even though I do this at work when I'm fault tracing stuff, the new environment of the boat kind of made me forget about this at first.

 

Anyway now on to electrics!

 

Cheers,

 

Ben

Heron