Struggling Morso with back boiler

[David Mack]

The header tank is in the wrong place. There should be a vent pipe rising continuously from the upper boiler connection, with an inverted U at the top terminating over the header tank. That way, if the water in the boiler should boil, the resulting steam can be safely vented. With the layout shown, boiling will result in very hot water being pushed out of the header tank.

[luggsy]

Is the  pump pushing the water to fast through the back boiler ? I had the same problem with my reflex diesel stove ended up putting a PWM controller on to slow the water flow through the boiler works perfect now , just a thought 

[Boater Sam]

10 hours ago, David Mack said:

The header tank is in the wrong place. There should be a vent pipe rising continuously from the upper boiler connection, with an inverted U at the top terminating over the header tank. That way, if the water in the boiler should boil, the resulting steam can be safely vented. With the layout shown, boiling will result in very hot water being pushed out of the header tank.

Agreed the "header tank" connection should be on the high point of the flow pipe to ensure any steam/boiling over, goes  into the tank and also to vent the pipework properly.

It would be unusual to have a "U" vent pipe over the the tank and a fill pipe from the bottom on a boat installation, the tank has normally just a bottom connection to function as an expansion tank, boil over and venting air just bubbles up inside.

A sealed system would be possible but I avoid them on boats, the complications of temperature and pressure release valve and expansion vessel is not warranted in my opinion.

On a boat, keep it simple, less to go wrong.

[Alfies Dad]

On 08/11/2018 at 21:06, Boater Sam said:

As a heating designer (retired) I can make the following observations.

 

1   Single pipe circuit such as this are sluggish and not efficient. The radiators will be cooler as the water goes round the system.

2   The flow (hot) pipe dropping to the floor from the boiler seriously reduces any flow due to gravity, hence the pump. I detest pumped solid fuel fired systems on safety grounds.

3   On single pipe systems it is advantageous that the flow pipe to each radiator  goes to the top of the radiator. Using opposite bottom connections drops the radiator efficiency by 7%.

4   When dealing with boilers that are underpowered for the heating load as in this case it is an advantage to be able to turn off any radiator that does not need to be on.

5  Thermostatic valves are a no-no on such a system.

6   Running a gravity only system is the best way to use a solid fuel boiler. The flow pipe rises from the boiler to gunwale height, feeds the radiators at the top, return from the opposite bottom corner, return at low level to the boiler.

7 My system has a Squirrel at the rear of the saloon 14 ft from the front door feeding a 134litre vertical calorifier, 3 radiators with thermostatic valves, no lock shields, and a pipe loop to the front of the boat to prevent condensation on the water tank. All pipework is 15mm, all gravity circulated in a 50' boat with 3 Houdinis, 4 single glazed windows, 4 small double glazed ports, side doors. No insulation in the floor, 2" polystyrene in walls and deckhead. It burns 100kilos of anthracite/egg mix every 2 weeks in winter and is toasty.

Sam.

I have a pumped system (pump failed!) that I want to convert to gravity feed.

I have a friend who has installed several systems on his and other boats and he says (it seems to be the general opinion) that I need to install 28mm pipe. Is this true? Yours said 15mm.

I have a Morso with BB running one small radiator about 30feet away at the rear. I want to add my calorifier to the system. Also at rear opposite to the rad. Current pipe work is15mm running down to and feeding up from the floor. The small radiator was a replacement last year so the system is fairly clean. The whole boat is only 50ft so don't need loads of rads. When working the boat is nice and warm with no need to get stove resembling Dante's Inferno! ?

Wondering if I can get the system working just by resiting the header and raising the supply pipe?