2 system boilers

[KevC1]

Just wanting some ideas from any heating installers.

I've been to quote for a very big house. The heating load is 57kw.

I was thinking the best way to achieve this would be to install 2 30kw system boilers side by side, with an unvented cylinder.

The heating system is in 2 zones, so ideally one boiler could deal with one zone, and the other could deal with the other plus the cylinder.

Does this seem sensible? Or has anyone done it in a different way?

Thanks for any ideas.

 

[kevindgas]

no it would be better to run both together in series so if 1 fails the other can supply 1/2 the output to each circuit.

 

[Boilerman2]

Link 2 boilers via a low loss header, as has been said, this arrangement will give the householer a back up WHEN one of the boilers breaks down (which it will!)

 

[Temprise]

Pipe the two boilers together on a reverse return arrangement. If they are not piped up in this way then one boiler will do all of the work and wear out quicker.

Regards

 

[ajstoneservices]

Wot he said

 

[Biggles..]

are you sure your heat calcs right, normal modern unventeds require a 20kw coil,priority hotwater or stagnated heating times wont work in a building of this nature.

reverese return boilers is a waste of time in this instance,normally youd need equal sized boiler with in built pumps,the only added benfit would have been if the rads were pipe reverse return then sizing of pumps etc would have been childs play.

best option is cascade 2 boilers(common flow and return with nrv's) into a low loss then on the load side seperate your heating ciruits to be vt and your hot water circuit to be ct.On boiler side it would be worth while adding mikrofil and your external presure vessel(boilers wont be big enough).pump solution would be one for each circuit, normally upsd or uped for redundancy.

boiler size would normally as a rule 2/3 of total load, so you should be looking at 2x45s for true redundency.

2x 30 viesmans will be naff,bad boiler bad design, you should consider 2 broag quinta 45's on a flue header.if you cant work out the boiler hydraulics broag sell it on a skid,all you have to do is pipe up the load to the headers,they even do a controls package bolted on.

£20k for flooring, a proper plant room should make them flinch too much if they want a proper job.

Lee