Urgent possibly daft quesion!

[24shaw]

I have been tasked with the design of a heating system for a sports changing room facility, the building is to be heated using underfloor heating throughout, with an Andrews water heater supplying the hot water for the sanitary ware!

My question is, what boiler do I use? If I use a heat only boiler, do I need to feed primaries to a cylinder before I can feed the underfloor heating manifolds? Having never designed a system utilising water heaters I am confused! Surely it can't be as simple as sizing a heat only boiler which feeds directly to the manifolds?

or can a water heater provide heat for the underfloor? or is this primarily for the hot water supply?

Any help with this would be great?

 

[Toddyplumb]

I am gonna be blunt here im afraid . You are clearly out of your depth and a forum is not really the place to get this sorted. You should pass the job up in my opinion. No offence intended.

 

[24shaw]

great advice that mate! 🙁

the work is obviously going to be overlooked I was just tasked to look into it....

just to clarify, I have already sized the underfloor heating, and all the pipework to the sanitary ware

 

[Robtheplumb]

Ring Nu-heat, talk to them.

 

[24shaw]

the underfloor heating is already sorted, and pipework sized, I just need to know what the correct boiler/cylinder to use is, when the client wants an Andrews water heater supplying the hot water.

I could quite simply design the system utilizing a simple heat only boiler with unvented cylinder?

 

[Robtheplumb]

You need to tell the custard that what he wants is not the best way to go, fit a heat only boiler and a thermal store, lot less hassle

 

[24shaw]

You need to tell the custard that what he wants is not the best way to go, fit a heat only boiler and a thermal store, lot less hassle

I thought this, but as I am new to commercial design I didnt have much confidence.

If the customer was to insist on the Andrews, what would be the best way to do this?

(thanks for the helpfull response)

 

[Toddyplumb]

Its a water heater you dont have a cylinder , get it overlooked asap.
I stand by my initial advice

 

[tamz]

Toddy is right here. You are well out of your depth with this. You don't even know what an Andrews is. Who "tasked" you to design it?

 

[24shaw]

I must admit I don't know the Ins and outs of a water heater as this is my first design using them! I do know how they work though!

All I'm really asking about is the boiler for the heating side of things? As the underfloor only requires 22kw.

 

[tamz]

If the underfloor only needs 22kw that is all the boiler you need. The water is covered with the Andrews heater(s). You will need to watch the gas pipe sizing.

 

[migoplumber]

if you dont want a world of call backs as "the design engineer" i would suggest you follow the above 'out of your depth advice'
we all start somewhere, but if i were in your position i'd call in someone with experience - pass them the job, and ask them to show you how its done.
andrews, water heater, underfloor heating - it dosnt add up to a system.
good luck tho.

 

[moony]

can he run the underfloor heating off a normal heat only boiler though?

would be intersted to know the answer to this myself as ive never come across it.

 

[tamz]

He can run the underfloor off anything he likes but not the Andrews. A direct fired water heater does what it says on the tin. Heats water (for taps).
Direct fired water heaters are used on most commercial jobs where there is a big peak demand as they have high recovery rates. Nothing else is really comparable for cost, recovery rates, size of unit, ease of installation etc etc. Most will need commercial tickets to fit.

 

[moony]

underfloor heating runs best at 55 degrees? how is this maintained running off a heat only boiler ? is this done with the dial on the front? as most boilers run between 70-80.

i know there is a blending valve on underfloor is it done with this? if so how - it just keeps topping the circuit in the underfloor heating up with the heat from the flow?? if this is the case then would the return temp ever go low enough for the boiler to run in condensing mode50ish degrees?

sorry for all the questions i have done underfloor heating courses but its been more on the installation side of the pipes and manifolds rather than the how and what of the boiler side.

 

[stevetheplumber]

yes you can run the underfloor on a heat only boiler water is mixed at the manifold to get optimum temps running just the heating allows low tempratures as no cylinder to heat
andrews water heaters are stand alone units which produce large amounts of water with very quick recovery

 

[24shaw]

After looking into water heaters I now understand how my initial question comes across looking like I have no idea!

The design has been looked into by the senior engineer who has gone for a water heater fed from a booster set and a 35kw boiler(to allow for 50% expansion)

Does anyone know where I can find information on group mixing valves? For required flow rates etc?

 

[Toddyplumb]

Rada , commercial section of Mira will sort mixing valve. Im sure the other large manufacturers will have commercial as well

 

[aceplumber]

we do alot of work for a large london borough council , they insist on "Horne" mixing vales , very expensive but best on the market , also tmv's work best with equal pressure , eg. both hot and cold to be mains or both tank fed , not one of each .