For the heating gurus - radiator runs

[TandC]

Very early thinking through the radiator and heating run layout on our new build.   

 

• 45ft x 10ft.    Four radiators and a towel rail (not yet done the sizing of these yet)
• Webasto Thermo Top Evo - 5kw marine version 
• 90lt calorifier in the engine bay (Yes, not necessarily ideal but it's the only place for it and no I can't relocate it)
• Header tank in a head-height cupboard 

 

My first query is re. running the hot feed to radiators on both sides of the boat.  

 

I could either run a supply feed along the starboard wall, with a spur running across the rear bulkhead to feed the port radiators. 

 

Or,

 

I could go along the starboard wall, across the bow, back down the port wall. 

 

The  first option is slightly shorter in supply length - not needing to extend beyond the end radiator, round the bow, all the way back. 

 

 

Not sure what the experts think?

 

 

Thanks in advance

 

 

 

 

 

 

[GUMPY]

9 minutes ago, TandC said:

I could go along the starboard wall, across the bow, back down the port wall. 

This is how mine is done in 22mm,  obviously you will need a return also in 22mm.

mine is through trunking at floor level with vents in the top of the trunking  along its length allowing warmth out everywhere.

The flow and return on mine are connected  at the far end so even if everything is off ( some rads are on TRV) there is still a flow back to the boiler.

Been working well in the 11 years I have owned the boat. The only slight difference is the the output from the boiler comes to a T junction and goes left for the heating and right for the calorifier which is plumbed in 15mm to give some resistance to flow to favour the heating, having said that it all heats up evenly. 

 

I did spend time balancing the rads when I changed the boiler but haven't touched it since

[Bee]

I would think option 2 might circulate easier but for me it would depend on the layout of the boat, if the back of the boat has beds, storage and poorly ventilated corners I would run the pipes through there just to get warmth into the potentially mouldy bits.

[GUMPY]

1 hour ago, Bee said:

I would think option 2 might circulate easier but for me it would depend on the layout of the boat, if the back of the boat has beds, storage and poorly ventilated corners I would run the pipes through there just to get warmth into the potentially mouldy bits

My Eberspacher and calorifier are in a cupboard just forward of the engine at the back and the pipes finish opposite under the bed on the other side 10ft past the last radiator. So as far as places with no warmth go there aren't any.

The person that put Loddon together in the first place got it absolutely right.

 

[David Mack]

Option 1 with two sections in parallel will have less resistance to flow, so should get better circulation (important with the feeble pump on a Alde 28xx gas boiler). But it will be more difficult to balance the radiators as changes on one side will affect the other.

In practice I suspect it doesn't much matter. Considerations as to which end of the cabin it is easier to locate the cross pipes unobtrusively, or Bee's point about providing some heat in potential damp spots may be more important.

[BEngo]

Option 1 will be a double-barreled sod to balance, because you have to get 3 different flows sorted to similar rates.  Two of them will absorb  heat continuously but the calorifier will only absorb heat until the tap water is hot.

 

Don't  forget to connect the header tank to the return pipe and to vent the flow pipe over the header.  That way if it boils the water will be forced back into the header tank, whichever way it goes.

 

N

[David Mack]

22 minutes ago, BEngo said:

Option 1 will be a double-barreled sod to balance, because you have to get 3 different flows sorted to similar rates.  Two of them will absorb  heat continuously but the calorifier will only absorb heat until the tap water is hot.

More difficult certainly, but not insolubly so. Option 1 is similar to many house layouts which have one branch serving the downstairs and a second branch for upstairs, and a third for the hot water tank.

[TandC]

2 hours ago, BEngo said:

  

 

Don't  forget to connect the header tank to the return pipe and to vent the flow pipe over the header.  That way if it boils the water will be forced back into the header tank, whichever way it goes.

 

 

 

Thanks - what exactly do you mean by vent the flow pipe over the header please? 

 

[BEngo]

Like an old-style  non-pressurised domestic central heating header tank.

 

  Feed pipe ( usually 15mm )  from the bottom to the return pipe ideally but not essentially near the boiler, vent pipe from the flow,  entering the tank above the normal water and overflow levels.  The domestic vent is often 22mm, but a boat system is unlikely to be so big it will need anything bigger than a 15mm vent.

 

N

[MtB]

6 hours ago, David Mack said:

More difficult certainly, but not insolubly so. Option 1 is similar to many house layouts which have one branch serving the downstairs and a second branch for upstairs, and a third for the hot water tank.

 

Yes but bear in mind household systems generally have one helluva meaty, power-gobbling pump compared to the feeble, power-sipping devices fitted to narrowboat heating systems.

 

 

 

[TandC]

Okay thanks - for now, I will plan for the "right round the boat" option, as opposed to splitting.   More questions to follow as we get there.  Thanks all

[rogerc]

on a boat i would just use a single pipe all round the boat no need for flow and return. and the feed and expansion are usually a common pipe. your boiler will be a third or quarter of a 3 or 4 bedroom house! if you cruise a lot put in a heat exchanger for £30 to use waste engine heat and isolating valves for the heating and hot water so you can set priorities. 

[GUMPY]

30 minutes ago, rogerc said:

on a boat i would just use a single pipe all round the boat no need for flow and return. and the feed and expansion are usually a common pipe. your boiler will be a third or quarter of a 3 or 4 bedroom house! if you cruise a lot put in a heat exchanger for £30 to use waste engine heat and isolating valves for the heating and hot water so you can set priorities. 

So how does the heating fluid get back to the boiler if there is only a single pipe?

[Tracy D'arth]

I think he is talking about a single pipe system with radiator flows and returns connected to the same pipe. Radiator flow goes in at the top and the return out at the opposite bottom tapping. It does work but not as well as a 2 pipe system and the radiators get progressively cooler as you go away from the boiler.  Was common in houses as background heating on solid fuel back  boilers years ago.

[Tony Brooks]

Mine was single pipe when it was on the Ellis boiler and gravity circulation, but the radiator feeds and returns were in the bottom pipe. I worked well.  Really just like the original central heating system at home.

[BEngo]

We had a coke fired single pipe heating system at home in the 60's.  Despite Dad's best efforts at  boiler stoking, and he was an ex LMS fireman,  never did succeed in getting all the radiators warm at the same time. The room with the boiler was warm though🙂

 

N

 

[rogerc]

any system depends on the boiler and radiators being matched.  a single pipe system is poor if you have 10+ radiators getting progressively cooler. but it is quite adequate for 4-6 radiators and cheaper. its a balance.