which system and what price

[stanmore]

I wonder if i can gain some help and guidance

We recently moved into a Victorian semi detached house with accommodation over three floors plus a full size cellar area. The existing set up is a Worcester 30 CDI regular boiler (only 4 years old but this has never been serviced) with an open vented hot water system (located within the cellar) and two tanks in the roof space, presumably a cold water storage tank and a top up tank for the c/h. The radiators on the ground and 1st floors appear to be circa 1970 but fitted with new TRV's possibly around 4 years ago when the boiler was replaced. The upper floor which houses 3 of the 6 bedrooms has modern K2 radiators with Drayton TRV's so presumably was updated at some point and doesn't need any work as far as i can tell. The property has only 50mm of loft insulation and timber framed single glazed windows with a total floor area of 240m2 excluding the cellars which are original condition with only a radiator in the boiler/utility room.

Having moved into the property the c/h and hot water systems began to play up and we knew that the systems would require work at some point. It also became evident that the existing h/w tank was too small for our needs and that some of the radiator sizes were too small with the landings and w/c not fitted with any. We currently have a bathroom, shower room, utility and w/c with two adults and 2 young children in the property, the shower and bathroom are used frequently and we previously enjoyed a Worcester Greenstar combi at our last property.

The heating engineers/plumbers that we have had round have suggested the following variations either a Valiant Ecotech 637 and a Valiant 250 Unistor, the Valiant Ecotech 637 with a 250ltr Megaflow or a Viessman Vitodens 200 with a Viessman Vitocell 200 V 250 ltr. They have all commented that the existing boiler is too small for the property and that they can not easily reuse the existing boiler. As part of the works we have asked them to quote on is the replacement of the 6 old radiators and the installation of 4 new ones with new TRV's on all - they propose to reuse the exisiting pipes but replace the uprights to the rads, they will also remove the old water tanks and install a new run of pipe to the gas meter. They are also proposing to install a new water main as the existing is in lead and a shared supply with our neighbor.

My questions are
I presume as all three have recommended a unvented h/w system that this must be the most appropriate rather than a high out put combi ?
We have the space in the cellar for a cylinder and boiler but i imagine that a combi is cheaper to buy and run ?
All have now said the Worcester B are not as good as they used to be hence they have not recommended one of their boilers ?
If we decide to install a Valliant boiler would we not be better to install the Valiant cylinder over the Mega Flo?
How an you tell which cylinder is best ? if i install a dual coil cylinder now thinking ahead to possibly solar will this have any draw backs ?
How good is the Viessman set up in comparison and is it worth the extra ?
What make of radiators should i look for or avoid and the same with the TRV's
Should i ask for a Magnaclean (sp) to be installed ? as nobody has suggested this.
They have all mentioned flushing the system but have not mentioned a power flush is this something that i should look for ?
I have calculated the boiler output and radiators based on the various on line calculators and they all say circa 35kw inc 2kw for h/w.
As part of the work i also need to install radiators or heating within a timber framed double glazed conservatory how do i calculate the output for this room ? internal measurements circa 16m2.
The Viessman installer has suggested weather compensation but as our house has quite poor insulation values will this be worthwhile ?

Are there any other questions that i should ask that would help with selecting the correct guys for the job, one was recommended by a friend, the other we have used before and the third from a website.

 

[ianniann]

If you want a combi then tell them you want a combi. The installer has no clue wheat your lifestyle is. If you had a combi before and it worked for you then get another.

Flushing and the magnaclean are strange issues where everyone has a different opinion. With a relatively new condensing boiler already in place, the system should be fairly clean. Should have been very clean four years ago. Power flushing might be necessary if there was a significant sludge in the system. The magnaclean is a device which can help to remove potentially damaging pieces of metal and rust. There shouldn't be many in there when the boiler is installed and new ones shouldn't show up very often, but they do seem to appear.

Weather compensation doesn't really depend on the level of insulation, although obviously your house's reaction to outside temperature does depend on it. The weather compensation controller learns how to modulate the heating based on the readings it gets over a period of time. You will also be able to change certain settings so that it heats up more or less quickly according to your preferences. The outside temperature is just a way for the controller to guesstimate where the heat loss from the house will be along it's learned scale, and hence how hard it will need to work to smoothly reach the setpoint temperature. Kind of up to you really whether you want to go this extra step, you can get most of the benefits with a simpler intelligent controller without weather compensation.

Possibly a little insulation would be a cheaper option than jumping to a bigger boiler?

 

[muggles]

They are also proposing to install a new water main as the existing is in lead and a shared supply with our neighbour Would be a good idea, especially with an unvented cylinder, my personal recommendation would be to ask them to install a 32mm main if they're doing it, it'll cost peanuts more and should give you a better flow rate

My questions are
I presume as all three have recommended a unvented h/w system that this must be the most appropriate rather than a high out put combi ? For your size of house, especially when you have two children (who will inevitably become teenagers and use a lot more water!) a combi would be completely unsuitable, unvented cylinder is the only sensible option here

We have the space in the cellar for a cylinder and boiler but i imagine that a combi is cheaper to buy and run? Yes, but cheaper isn't the same as better. If you get a combi I think you'll regret it sooner or later

All have now said the Worcester B are not as good as they used to be hence they have not recommended one of their boilers? They're OK but can be a bit of a pain to install and service. We almost always install Vaillants, it's down to installer preference to some degree though

If we decide to install a Valliant boiler would we not be better to install the Valiant cylinder over the Mega Flo? There is some degree of argument for this, Vaillant boilers and cylinders can 'talk' to each other so when set up correctly it's claimed that it's a bit more efficient. I have no experience of Vaillant cylinders though, I like OSO Super S cylinders for a number of reasons, and I'm not keen on 'genuine' Megaflo cylinders

How an you tell which cylinder is best ? if i install a dual coil cylinder now thinking ahead to possibly solar will this have any draw backs? Which cylinder is best is a much-debated point. From my own point of view, I look at heat-up and reheat times, heat loss (some cylinders are better insulated than others), warranty, ease of installation (something that's trickier to install will inevitably cost more) and maintenance, for larger properties whether a secondary return connection is available, and general design. If you think you will put solar in at some point, then go for a twin-coil cylinder now, you can always have your engineer connect both coils up to the central heating for now. No drawbacks until you come to install the solar, which isn't cheap and will take forever to pay for itself!

How good is the Viessman set up in comparison and is it worth the extra? Someone with more experience of Viessmann will have to answer this one, I don't know enough about them to comment

What make of radiators should i look for or avoid and the same with the TRV's Stelrad Compact or Softline rads (Softline are Compacts with curved panels, look quite nice but up to you as to whether they're worth the extra money), Danfoss-Randall RasC2 or RasD2 valve packs, IMHO RasD2s look a lot nicer and Danfoss will tell you they're a better valve but they are a bit more expensive

Should i ask for a Magnaclean (sp) to be installed ? as nobody has suggested this. Generally I'd install one to protect the boiler where a boiler is being fitted onto an old system with old rads, however as you're intending to replace your rads and at least some of the pipework a system flush should do you nicely, but if you want one ask for one, it won't do any harm to have it

They have all mentioned flushing the system but have not mentioned a powerflush is this something that i should look for? Ditto my comment about replacing rads and the Magnaclean

I have calculated the boiler output and radiators based on the various on line calculators and they all say circa 35kw inc 2kw for h/w.
As part of the work i also need to install radiators or heating within a timber framed double glazed conservatory how do i calculate the output for this room ? internal measurements circa 16m2. Try the Energy Saving Trust's website, I believe they have a calculator on there

The Viessman installer has suggested weather compensation but as our house has quite poor insulation values will this be worthwhile? All helps, WC is designed to make your system more efficient but it will require setting up correctly, I'd also suggest that they install larger rads so you can run them at lower temperatures, as this helps with efficiency too. And get your house insulated better, it's not expensive and will save you money very quickly, I've recently paid a mere £5 a roll for loft insulation from Homebase

Are there any other questions that i should ask that would help with selecting the correct guys for the job, one was recommended by a friend, the other we have used before and the third from a websiteIf you're happy with the one you've used before, use them again, if you're not, go with the one your friend recommended. As your house is over 150 square metres, your installer should be splitting it into two heating zones plus a hot water zone

 

[transam]

Well Muggles u certainly deserve , some thank's after wading your way through that post !!!!! very good!!!

 

[greemyamochop]

Have very recentley moved into exactly the same property as you so know your concerns etc

I fitted a 30cdi and a premier plus 350litre unvented cylinder too and theres no way a combi will suit the size of property your talking about.

If i can be of help let me know as just finished my installation and its working like a dream

 

[muggles]

Well Muggles u certainly deserve , some thank's after wading your way through that post !!!!! very good!!!

Cheers

 

[stanmore]

Muggles - thanks for all the advice very useful, i have had a look at the Oso cylinders and these look impressive, why do you install these ? and what advantages do they have over a Range or Viessman cylinder ?

The quote for my new water main states 25mm alcathene can you get this in a larger size or do you mean the copper run from the stop tap onwards in 32mm ?

As i also have a 5 burner gas cooker i presume that the gas main should be run from the meter in 28mm as a minimum as it will need to run circa 10m from the meter to the boiler

 

[muggles]

No problem. I install the OSO cylinders for a number of reasons, I'll list some in no particular order below, along with some comparisons with the Range cylinders...I've left Viessmann out as I can't find enough info on them, but added in Megaflo as the market's 'default choice' and because you mentioned them earlier:

1) Ease and neatness of installation - because all the connections are in one place, on top, pipework can often be kept tidier. Indeed, on installations such as new builds and compete renovations, it is often quite easy to run all the pipes behind the cylinder so that when the installation is complete, no pipework is visible at all, with the exception of the pressure relief which needs to be visible. A lot of customers seem to like this. The expansion vessels are also nice and neatly hidden away under the lid rather than being hung on the wall taking up space. By comparison, the Range cylinders have connections all over the side, meaning lots of visible pipework, and require a separate wall-hung expansion vessel. Megaflo cylinders do away with the expansion vessel but still have the pipework issue.

2) Performance - OSOs are among the fastest cylinders to heat up and recover on the market. Taking your Range as an example comparison, and using a 250l cylinder for all, the OSO can heat up from completely cold in 27 minutes and reheat in 19 minutes, the Range takes 27 minutes just to reheat, and whilst I can't find any figures I'd say a calculated estimate of 40 minutes to heat up from cold wouldn't be far wrong. A Megaflo takes 23 minutes to reheat, so probably around 33 minutes to heat up from cold, so of the three OSO cylinders are the fastest to heat up and reheat.

3) Efficiency - how much heat is lost over 24 hours. Again Range fall down here by avoiding quoting actual figures as far as I can see, Oso are slightly behind Megaflo here at 2.11kwh against 2.09kwh, but they're so close it makes almost no difference. Some cylinders are much worse, and this is important as greater heat losses will result in higher fuel bills (the more heat is lost, the more you have to put back in again).

4) Available connections - all Oso cylinders have a secondary return connection which allows you to create a pumped hot water circuit, giving almost instantaneous hot water to every tap. This is something you will almost certainly need in your house. Range cylinders have it on their larger cylinders, Megaflo cylinders have no such connection on any cylinder, and require the purchase of an extra part that gives a slightly non-standard final installation. SOLAR - here's OSO's weakness, there is NO option for a solar circuit on Super S cylinders. They do make a solar cylinder, which is a more traditional design similar to a Megaflo, but I'm not familiar with it as I don't fit solar. Both MegaFlo and Range have solar options, both will cost significantly more than the standard cylinders. Beyond the 'green' argument I have significant doubts about whether solar is worth the money and whether it actually ever pays for itself, but that's an argument for another day.


Hope the above helps from a cylinder point of view. When it boils down to it, it's things like performance, aesthetics, design and build quality that make me choose OSO, not everyone will agree but all installers will have their favourites and products they're familiar with.


As for the water main question, I meant get the new underground main laid in 32mm, it'll cost hardly any more and will give you all the performance you'll ever need. Incidentally it's MDPE not alkathene, but that's a niggly point... The other thing to look at is getting it run into your cylinder cupboard rather than the kitchen or wherever you were expecting it to go - there is a balanced-pressure cold connection on the cylinder controls which should be used to give best performance to mixer taps and the like throughout the house. I'd run a whole house off a balanced cold connection, with the exception of one outside tap which should be on the incoming main before the balancing valve, this gives a test point for the mains.


As for your gas pipe sizing, this is down to your Gas Safe engineer, the distance is one factor but the required heat output of both appliances, and the number of elbows required, are others. Only a site visit can really give an answer to this.

 

[stanmore]

Muggles,

thanks again for a very detailed answer, i only wish you lived in my area as i would give you the job if you wanted it and i could afford you !

My engineer stated that the water board won't connect a 32mm to the main on a domestic property ! however he uses a boring device to lay the new main so i wonder if the max for this is 25mm. I wonder if i would be better to dig up the drive and lay the larger 32mm if i can and foot the £200 difference in the quotes for laying the new main. As the drive is also block paved it would be easy enough to do.

much appreciated

 

[D_Hailsham]

Have very recently moved into exactly the same property as you.

Does "stanmore" know this? Which of you are "The Others"?


Use Boiler Size Calculator to find the size of boiler required. The result includes 2kW for the hot water cylinder.

 

[stanmore]

greemyamochop

can i ask you a couple of questions ?

Did you also replace the watermain ?
Did you replace all the pipe runs and rads ?
Power flush ?
any tips for what to avoid or look for ?

I presume your boiler and cylinder are within the cellar so the water has to travel 4 floors to the shower/bath on our the top floor ?. One of the guys has suggested a secondary h/w circuit with programable time zones to have quick access on the top but i feel that this is a luxury and we need to try and reduce the cost of the system - any thoughts ?

Have you put the c/h in 2 zones or 1 ?

I have seen a few premier plus cylinders and these look like good value but it is quite confusing with the choice especially now the Oso Super S has come up ! Waht made you chose the Sanaton ?

The quotes that i have had to include the boiler, cylinder, controls, 9 new radiators and TRV's patched into the existing pipe work with a new 28mm gas run and removing the old tanks from the attic etc these have ranged from £5,800 - £7,600 obviously with some difference in kit.

If i had the time i could tackle some of it but with a baby due in 9 weeks and work i don't have the time or energy but also don't want to feel i have been taken.

I have priced all the kit excluding copper and again this various between £3-4k for should i hence expect to pay circa £2,800 - £3,600 for the installation including copper runs etc