Boiler / Megaflo combo - Plumber confused and so am I!!!

[VinnyD]

I'll get to the point... Have a plumber who has been bought in by my builder to install the central heating system. I wanted a heating cylinder solution to allow for mains pressure hot water through my showers and bath. Was recommended a Megaflo solution. He suggested I get a 250DDDD direct unvented cylinder, combined with a Valliant 637 system boiler. Cylinder installed in loft and boiler in laundry room downstairs. House is a large 4 double bedroom house, with 2 bathrooms (one with a bath and thermostatic valve shower, the other with just the shower downstairs). I have 6 standard radiators, 2 towel rails, and 3 wall mounted vertical radiators in the 46sqm kitchen/diner (each one chucking out 1500KW). Using all this will be 2 adults and 3 kids (under 13).

I have heard conflicting advice about which boilers and cylinders to go for, and upon searching existing posts I cant quite work out what options are right for me. Hoping you good people and professionals can clarify for me please. Specific questions are;

1. Given I have one boiler, which will be covering the heating and the hot water, is the 637 sufficient, or indeed is it over the top?
2. Is an unvented direct cylinder (250DDDD) the correct choice / size?
3. Any advice on where I can buy from a reliable online merchant?

thank you all in advance.

V

 

[lame plumber]

I dont like vaillants, but thats my opinion, a 250 cyl should be ok, but I like to keep all the gubbins in one place if possible, cheaper to install and repair. Buying online is done from experience, and buyer beware. Are you happy to save now and then be told by your plumber in 6 months time when something fails, not my problem, you bought it, you sort it. So its upto you, you have been advised but your plumber isnt going to have to worry if its all ok as your supplying the kit, there is a reason why you pay a bit more to get a proffessional to do the whole job. Get a whole house heating requirement done, then youll know exactly what size boiler to fit!, you plumber should do this if he is doing everything, but if your buying he may well have just gone for a big boiler and decent sized cyl.

 

[Derek Hardman]

Im not sure why your plumber would be confused by this? I am not a vaillant fan either (but I am Worcester Bosch Accredited so Im biased), the only way to assure the boiler size is by calculating the requirements, if this is confusing your plumber, with all due respect you need a different plumber on board.

 

[vern]

Either you posted the wrong info or get a new plumber Megaflo 250 DDDD is direct and has four immersions! Not heated by the boiler, you need A 250 indirect go for a twin coil if sticking a 637 up it!

i think your info is wrong as I am still waiting to come across a 1500 KW radiator

 

[Derek Hardman]

Haha, I didnt even look at the rad size, 1500kw radiator? no need for decorating one wall then, the radiator will be mahoosive!

 

[TBServices]

You either trust your plumber or you don't. Personally I wouldn't trust a plumber who had been forced on me by a builder. You should obtain at least 2/3 estimates and opinions for the work required, preferably from recommended plumbers.

System boiler and Unvented cylinder is the best setup, but as vern said, you/the plumber got your facts wrong. You should also check he is G3 qualified as well as gas safe.

 

[vern]

A little off topic, I went to a house well bungalow 2 weeks ago that had a Vaillant 637 with 5 single rads and 1 towel rail, feeding a vented 36"x18" cylinder only one bathroom with an electric shower, 2 lovely elderly occupants, I was there changing a couple of TRV's, I mentioned the boiler and who had spec'd it etc, oh the builder who did our block paving lmao

 

[stoker122]

I would fit a 831-837 downstairs with the combi doing the kitchen and utility and the cylinder feeding the bathrooms, cuts down dead legs.

 

[TBServices]

A little off topic, I went to a house well bungalow 2 weeks ago that had a Vaillant 637 with 5 single rads and 1 towel rail, feeding a vented 36"x18" cylinder only one bathroom with an electric shower, 2 lovely elderly occupants, I was there changing a couple of TRV's, I mentioned the boiler and who had spec'd it etc, oh the builder who did our block paving lmao

Exactly my point about builders. Only interested in one thing.... £££££. Always better to find your own trades people when undertaking building works, as the only person a builder will recommend is the guy who he can charge a fortune for, but will work for as little as possible.

 

[plumber0808]

I agree with lame plumber, try to position it all in one place off possible & get them to supply and fit for the reason lame stated.

personally don't agree with the comments about the builders not all of them are bad.
it depends if the builder is any good as there are plenty of poor quality ones about.

I do work for builders, one in particular the jobs are run well and on time with the builder running the trades.
I charge him, he charges the customer. Fair enough he's paying for the work and running the job so he should charge for doing so

 

[lame plumber]

dont like builders, just quoted for a load of work and custard accepted and booked me in, the builder then did it and left me arguing with the custard that a callout to cut of a gas supply in the kitchen is going to cost her more than £8 if Ive not got all the other work quoted!!!!!!!!!!!!!!!!!!!!!!! I only said £8 plus comp end cap, as I was expecting a £500 labour job!!!!!!

 

[VinnyD]

I've probably got the info wrong on the rads - heating engineering ain't my day job, sorry. I've got 3 tall vertical double panel radiators...approx 5000BTU each.


I think, to be fair, half the confusion is I'm going through the builder who don't really know much about heating. I will speak to him direct. I want to be clear, though, before I go to him so I'm not left in any doubt when he tells me what will no doubt be sound advice.


So, if I'm expecting to heat radiators and hot water for showers/bath, an indirect unvented cylinder running off a system boiler is the way to go? So in what circumstances would someone use a direct cylinder? If I've got the heating on, missus is doing the washing up, washing machine is on, am I going to get annoyed if I try and use the shower?


Great advice above though - thanks. I'm going to see if I can get the plumber to do heating requirements. I've learned a whole heap on the building side over the last 6 month build, and hoping to have picked up some nuggets about this too.

 

[kay-jay]

Direct cylinders heated by immersion elements are usually found in blocks of flats where use of gas is prohibited and is for hot water only.

 

[kay-jay]

You won't be annoyed in the shower if you get an unvented system

 

[kay-jay]

Yes. Indirect and system boiler is best for your demands/usage

 

[VinnyD]

Ignore last post. A little extra research has answered my question on direct vs indirect. Obvious really when you think about it.

Just two question folks.. 1) I'm installing the cylinder in my loft. Any particular installation pointers or concerns I should be aware of?

2) I've heard a bit on personal preference, but are there any boilers more suited to the indirect megaflo than others? Equally, are there any boilers not very well suited? I'm only looking at the Valliant system boiler because I've been told they are the best or most reliable.

Thanks again. Hope everyone is having a great weekend.

 

[VinnyD]

Thanks Kay Jay. Appreciated.

 

[kay-jay]

Main concerns are about load bearing. In a loft its good practice to lay 3*2 across the joists and overlay with with 1" best plywood and locate if possible over a loadbearing wall. All this helps to support a very heavy cylinder

 

[TBServices]

Any boiler will do. And if cylinder is going in the loft, make sure the joists are up to task and the platform is correctly constructed.

 

[GasmanxxxR1]

wouldnt go for meagaflow, prefer oso or similar, not internal bubble

 

[leethegasman]

Just two question folks.. 1) I'm installing the cylinder in my loft. Any particular installation pointers or concerns I should be aware of?
Yes the weight of the cylinder.consideration must be given to the loft floor construction is it suitable to take the weight .as a example we did a couple of installations in lofts and due to that particular roof construction we had to cross brace the roof trusses a min of five trusses to spread the load.