NMEA

Not sure why you mention the Z, you could not possibly have one on a CH system as they have no provision for a coolant pump, they are for cars as an auxiliary and rely on the car water pump. So, you have a TTC, how did you test the pump? I have come across humming before on a few occasions and it was caused by an ECU failure transmitting a constant current instead of a pulse to the pump, if you check the current at the pump during start up it will confirm if that is so.

The noise you describe certainly sounds like the dosing pump, being a solenoid pump these do make a noise but it is more of a tick than a knock there are ways of reducing the noise which is transmitted through the hull by using rubber mounts and rubber joining hoses to the pump. Most if not all of the noise you can hear will be transmitted not radiated so do not be tempted to use any kind of sound deadening jacket over the pump as the thing can not dissapate the heat and could fail prematurely. Yours sounds like air being circulated by the coolant pump, probably a good bleed, or better still an auto bleed pot just after the heater outlet.

I use the Pico one for boilers, gets very good reviews on Amazon. https://www.amazon.co.uk/product-reviews/B00NSKJWGW/ref=cm_cr_dp_see_all_btm?ie=UTF8&reviewerType=all_reviews&showViewpoints=1&sortBy=recent

If you give the 40 a decoke it is important to replace the glowplug boss with screen at the same time, it is an imortant part of the fuel vaporisation and efficient burn which will extend the period until the next decoke.

Your relatives or the relatives of people who die or become ill may again take a different view of an inappropriate or faulty device device, if it's aproved for use on boats there will be less of an issue. Its all about minimising risk and exposure in my view, but then again my risk and exposure is greater than most.

It's not you that needs to be convinced, insurers may take a different view. As somebody who installs potentially lethal (if poorly installed / maintained / operated ) kit for a living I accept that I am possibly a lot more risk averse (and possibly better advised) than most and do things by the book, your ship, your life your choice though as they say.

Take care when buying them too, read the leaflet carefully as some specifically exclude marine usage, of course that may just be the manufacturers ass covering, but still...

If you have a leak on the tank side of the pump it will not cycle, it will pull air in though. But I would not only expect all taps to splutter but the leak would be quite noticable.

Three degrees C for the stand alone froststat but from memory the frost protection on the Heatmiser is only adjustable down to 7 degrees.

Why not just fit the Webasto frost stat, cheap and simple and no reliance on timers. The Thermo Call option mentioned above is a brilliant piece of kit and will send you an alarm when the temperature drops, I have fitted loads over the past couple of years but they come at a premium price. http://www.webastomarine.co.uk/shop/vclose1.asp?prd=123548&cat=26

You will have no problem with that number of rads, in fact you have a better chance of the heater burner lasting longer than those with fewer radiators as yours is properly loaded. A properly maintained marine Webasto TTC will run at 10.5v contrary to popular belief, however if the glowpin is masked by carbon which happens after a while it will require a higher voltage to start. Battery voltage is not the peramiter to look for so check the voltage at the heater during start up as you may have resistance in the supply cables, usually at terminals and fuses wher corrosion has taken it's toll. If the volage is good then more than likely either needs a decoke.

The 3/16" stuff is so close to 2mm bore as to make no difference, it's not really a case of if it works but more if it works as it should, pople do all sorts of stuff with these heaters, sometimes they work sometimes not but to getting it working the best it can and reduce potential future problems just follow the instructions.

The 3/16" O/D stuff on the Mikuni site (virtually identical but not flared) is less than half that price. http://www.mikuniheating.com/Results.cfm?category=27&secondary=35

Take care! some of the larger gauges like yours have a tiny cross pin, but that should be fairly evident if it has one.

Absolutely agree, it is even possible that the head of water in the basin may not even be enough to open a decent NRV.

Diaphragm pumps have been around for milenia, you could probably find one made of leather in a maritime museum somewhere the Whale Gulper is just another diaphragm pump, abait a bloody good one. Some people just prefer the auto operation of a sump, mind you there is now a Gulper that has a sensor so switches on automatically, so if you get any drain bak it will keep cycling so the pump need a bit of a "fall"

Mmm, I doubt it will even be a marine spec one then, hope you have good batteries, if you want a copy of the marine install manual just drop me a PM with an email address and I will fire you off a copy.

Or indeed if one fitted a bi metal thermostat with high on off differential that turms the Eber off when the calorifier gets near temperature, override switch for when using the rads too. You should get the marine install instructions with the narrowboat kit, they are not online. In areas where there is poor ventilation or fumes present I often fit an extra skin fitting for the combustion air intake with an inline intake filter / silencer instead of the standard terminal one.

Central heating stuff.

Webasto say 25% for a good reason, Glycol is a very poor conductor of heat, I have cured poorly performing systems simply by draining down and refilling with the correct concentration. Use the Webasto specified concentration and retain enough for future topping up. My preference is for the Screwfix no nonsense anti freeze because their inhibitor is compatible and you can just top up with taht every couple of years instead of changing the coolant.

If you are plugged into shore power for any length of time then a GI is a very good idea, any recognisable make will be perfectly fine. You could even get one of the types that goes in the shore power lad to save on installation.

Was it removed for service and replaced by the technichian, if so then call them back as whatever it is (low voltage aside) they should be responsible for their work.

Not too bad but there can be difficulties and the instructions are piss poor and though water heaters are easy they are not plug and play on air heaters, personally I remove the MC04 and just have the Thermocall, though they will work together. On the loom where that MC04 has one red plug and one blue plug in the back you will find another plug labled diagnostics / Thermocall, that is where the TC4 interfaces with the W-bus but after that you will have some work setting up the other plugs, it's all there but you have to insert the pins in the correct place.

The only reason the 10 is not suitable for a narrowboat is they are 10kw, much too high an output, they run perfectly well on ULS red diesel though. Plenty of them on larger boats, tanks, coaches et. al. performing well (for an Eberspacher anyway)

The MV range of Chinese made heaters are what Mikuni UK began importing after the end of Mikuni production a while ago. I have an MV sales and service agency and have fitted a few to date. Impressions are that like the old Mikuni they are a decent if agricultural piece of kit, the model you mention is a clone of a much earlier Webasto model as you suspected. At £1108.00 for the 5.0 marine kit they are fairly competitive and UK back up and warranty is provided by Mikuni UK so you have comfort there, unless you buy a grey import, in which case you are on your own. They lack the sophistication of the current Webasto models and are a little noisier but yer pays yer money... Hope that helps. Edit to add that if an MY30 was being considered then the Airo 4.0 would be a closer match.