renovation tender - ufh spec

[crollorc]

hiya,

i'm starting to put together a tender doc for a low energy bungalow renovation.

we plan on using a 240l break tank, 3 bar booster pump and viessmann vitodens 100w combi. we would like to use wet ufh on the 160 square meter ground floor and are currently thinking of using 3 zones and 3 towel rails also connected to the ufh system.

i was wondering what details you would include in a tender doc with regard to the ufh to avoid as much grief as possible?

i'm new to this stuff so apologies for general cluelessness!

crol

 

[Agile]

To avoid grief I would suggest you get a competent heating engineer to produce the specifications!

UFH works on about 40 C typically. That will be warm for the towel rails but not hot!

More relevant will be how you control the mix of radiators and UFH. It is not as simple as it may look!

Tony

 

[crollorc]

thanks tony.

To avoid grief I would suggest you get a competent heating engineer to produce the specifications!

how detailed would those specifications be and how much would it cost roughly?

for the tender we're mostly concerned with ensuring we are comparing like for like on each of the renovation elements.

UFH works on about 40 C typically. That will be warm for the towel rails but not hot!

More relevant will be how you control the mix of radiators and UFH. It is not as simple as it may look!

we don't mind the towel rails only being warm as they will only be used to dry towels and there will be no other radiators.

i was hoping to use weather compensation for the ufh in combination with room thermostats to help prevent overheating but this is just based on what i've read online.

crol

 

[Agile]

we don't mind the towel rails only being warm as they will only be used to dry towels and there will be no other radiators.

i was hoping to use weather compensation for the ufh in combination with room thermostats to help prevent overheating but this is just based on what i've read online.

crol

A towel rail at 40C or less will not heat a bathroom! Covered in towels its heat output will be virtually nil!

With UFH turning it off with a room stat will then give you an hour of overheating due to the excessive thermal lag.

Properly set up with WC can give very good results though but it needs careful adjustment and then left to the controls to deal with it.

You have not said what you intend to do with this tender. I suspect it is to send to a builder! All the professionals here will be likely to say employ a heating engineer directly and do not involve builders.

Producing a tender from what you read on the internet seems to me like a recipe for disaster!

Tony

 

[crollorc]

A towel rail at 40C or less will not heat a bathroom! Covered in towels its heat output will be virtually nil!

the bathrooms will have ufh in addition to towel rails.

With UFH turning it off with a room stat will then give you an hour of overheating due to the excessive thermal lag.

yikes; doesn't sound nice.

Properly set up with WC can give very good results though but it needs careful adjustment and then left to the controls to deal with it.

do you think the wc in the vitodens 100w would be sufficiently adjustable? or would you recommend another boiler or wc system?

i'm a little confused about how wc would work in combination with multiple ufh zones.

You have not said what you intend to do with this tender. I suspect it is to send to a builder! All the professionals here will be likely to say employ a heating engineer directly and do not involve builders.

yes, a main contractor.

our architect is working on the detailed design. do you think i should be engaging the heating engineer now to provide input to this process? what level of detail should this be in?

would you separate the design and commissioning process? would this make the whole process more expensive?

thanks again,

crol

 

[Dan Robinson]

Most in house plumbers for builders are capable of cobbling a bathroom together, but designing a proper heating and hot water system is beyond them and you will almost certainly end up in the cack.

Get your own heating man in.

Or vet who the main contractor is using (references etc., make sure they have their own business rather than just working for a single builder).


The 100W is a budget boiler at a price beyond its worth. This is where you as the customer shouldn't be specifying anything other than performance and end results. What does what and how should be the domain of the person doing the work IMO. It is a royal ball ache when Consultants and customers start getting fresh with Google and thinking they have the right idea.

Anyway - look at the Evohome kit from Honeywell for controlling multiple zones through a central panel. they have specific kit for UFH.

Alternatively go to a UFH company like NuHeat which will design the UFH for you. Obviously this is built into their price but there are guarantees then as well as design liability passing to them.

 

[ALEC1]

or thirdy look at the vitodens 200 with vitotronic 200 which can control three zones trough their mixing valves

Beware of people like Nu-heat.. they will over sell the controls which make things more complicated than necessary...

keep it simple with one manufacturer of boiler and controls and one supplier of pipe...

 

[ALEC1]

You could do the whole house on one zone, if you wanted...

with one controller..... although if you had several different types of floor covering you would really want a valve for each floor type as each floor covering offers different thermal performance..

If the floor coverings are wood, this would be highest temperature circuit, and tiles on screed the lowest temperature.

 

[crollorc]

You could do the whole house on one zone, if you wanted...

with one controller..... although if you had several different types of floor covering you would really want a valve for each floor type as each floor covering offers different thermal performance..

If the floor coverings are wood, this would be highest temperature circuit, and tiles on screed the lowest temperature.

hi alec,

we were planning on having engineered wood floors mostly with tiles in the bathroom and ensuite.

how would the valves be setup and would the wc on the 100w work well with this kind of setup?

would you suggest using thermostats or just wc?

crol

 

[Agile]

You are asking very basic questions!

The replies are inter related.

To fully understand the answers you would need to study heating engineering for many months.

Odd you want to use a cheap basic boiler model but engage expensive architects and main contractors.

The Vito 200 series is very good indeed but like everything is more a question of how it is installed and commissioned.

Usually it would be possible to balance the flows through each loop to an extent to compensate for the thermal transfer rate of your different floorings.

In a well insulated property I would often question if it is worth having more than one zone for UFH on the ground floor.

A friend has 26 zones of UFH in his house. Including a zone for each of the seven toilets. But he has rather too much money to spend!

Tony

 

[ALEC1]

well the 100 won't work with the vitrionic 200! so you need to change boilers.

 

[ALEC1]

And what's the point of a booster tank with a combi?

 

[Richardthe3rd]

I used this company that are based in Eire a few times & they know their onions.

http://www.pipelife.com/ie/index.php

 

[crollorc]

I used this company that are based in Eire a few times & they know their onions.

http://www.pipelife.com/ie/index.php[/QUOTE]

cheers richard.

based on all the comments i will try to get some quotes for the work rather than include it in the tender.

next step is finding some decent heating engineers in ireland!