Mobile Home Heating System

Hi, I am redoing the interior & exterior of my 28 X 10 ft single mobile home completely.
Part is going to be replacing the old hot & cold water systems & installing gas water / central heating, based on a Baxi Gold combi I got a good deal on.

Ideally, I want the boiler installed & commissioned before I install the radiator circuit & rads, as I am going to be knocking down old partition walls & building new ones, etc. & I will have to remove the old cylinder (electric immersion) before moving a partition so would be left with no hot water unless I had the new combi set up first.

So, first question is: Can I get the combi commissioned with no heating circuit & use it just for water heating for now?

When it comes to the actual heating circuit, which must run within the mobile home, the only feasible design I can come up with is 22mm pipework run at skirting height from the boiler all the way around the inside of the exterior walls of the mobile home (short drop to under floor to go under one door), feed & return running together & teeing off in 15mm to each rad (4 rads in total, about 25m run). I would cover this with hollow skirting.

To clarify, the feed & return would run alongside each other in 22mm for 25m, each rad teed off the feed in 15mm (about 40cm each rad) & it's 15mm 40cm return teed into the 22mm return pipe. The return pipe would not loop back to the boiler, just terminate at the last rad.

My main concern with this would lack of clear flow on the return, so my second question is: Is this a good design, any problems likely?, anyone got any better ideas? Is 22mm a good idea or can I go all the way in 15mm?

Thanks in advance for your help,

Steve

Can you not get underneath your home? most mobiles have the heating mains clipped to the underside of the unit with the pipes rising through the floor for each rad, obviously good pipe insulation is required & I would recommend Fernox Alphi inhibitor/antifreeze in the system water

as above, why not under the home? Its pretty much standard. You don't say how many radiators and what sizes, but you could probably do majority of it in 15. A bit of 22 from the boiler to the first T is a good idea though.
Not sure about using the boiler without the rads, its physically possible but I'd want to get the go ahead from the manufacturer first just to protect your warranty.

Thanks for your replies to date, much appreciated.

Aha, didn't think of the potential issues with manufacturer's warranty, thanks for the prompt on that one!
I guess the simplest solution overall will be to do the runs to the first rad
( which luckily will be in the bedroom, which I am not altering much) & leave the rest until I'm ready.

At least then the engineer will have everything he needs for full commissioning then I assume.... hot water circuit + a one rad system.

I take it that no one can see any flow issues with running feed & return together in one big run stringing rads off it as I go then?

| can't get under the majority of the mobile home at the moment as someone in the past has built a rendered block wall skirt all the way around, with one access hatch only. Unfortunately from that hatch, due to the low central axle, waste stack & pipes, I can only access about 1/3 of the home from underneath. I do plan to remove the block skirt & replace with suitable accesses included, but don't want to start until I have done the other 10,000 jobs I have planned. If it comes to it, I might well get my club hammer out & make a few more accesses & sort it out afterwards I guess!

That got me thinking about running it all inside, which does make sense from a heat loss & insulation cost point of view & less to worry about regarding potential freezing weather.

It will only be 4 rads ...
600 X 900 double, 5494 btu in lounge
600 X 800 single, 2,802 btu in bedroom
600 X 600 single, 2,101 btu in bathroom
600 X 400 single, 1,401 btu in hall

So, does 22mm feed & return to first rad, then 15mm for the rest sound ok?

Cheers,

Steve

yeh 15mm for the others will be fine. After a while you get used to crawling under park homes looking for leaks, prv outlets etc... as you say though it would technically be better inside if you can do it.