Installation of new DHW and Central Heating system

Hello everyone

i'm having my whole central heating system replaced from an old open vented system with microbore pipework to a new combi system with the boiler moved to the airing cupboard, by a 'professional' council approved company.

The bolier i have chosen is the ecotec 837 plus, primarily because of the high flow rate (we tend to use many taps at once in our house). we've got an a bathroom/ toilet with an electric shower plus another seperate toilet dowstairs.

I have a few questions if any of you kind guys could help me out:

1. the installers/ plumbers have used plastic hep20 pipes under the floorboards (the pipework looks very messy), is this recommended? and what are the chances it could leak? plus they haven't insulated the pipework under the floorboards downstairs - they say these pipes are already thermally insulated, do i still need foam insulation? (this is what hep20 say: http://www.hep2o.co.uk/v2Othermal.htm)

2. the other thing is that the DHW outlet from the boiler is a 15mm coper pipe, however they have connected this to the rest of the hot water system using a short piece of hep20 pipe, which has a much smaller inside diameter.

Like all physiologists i look at things from a scientific perspective, and according to poiselles law, flow is proportional to the cross sectional area of the pipe squared for a given pressure drop. hence the smaller pipe would theoretically limit the flow rate(and so the expesive bolier would become a waste of money). ive tried explaining this to the plumber but he doesn't seem to understand and says that this doesn't affect my boiler because my boiler has a high flow rate?!?!?!?

they have done the same thing for the mains cold water inlet into the boiler, which itself is tapped off from the shower's water supply - i'm a little worried because if when i'm having and someone opens a hot water tap or flushes the loo, will this cause my shower to go cold or reduce flow on the boiler's DHW flow?

We are paying this company a lot of money to do this job and we want to make sure its done properly? i really hate telling builders/ plumbers/ engineers how to do their job...but i'm the one who will have to live with this and so i might as well get it right first time.

could someone please advise?

cheers...sorry for the long post and waffle

It seems that you may be using a firm that does contract work for a council in the mistaken belief that they will do a better job.

That kind of firm specialises in using poorly paid and inexperienced staff and using the cheapest methods of working like using plastic pipe.

I have today been asked by a housing association to replace a heat exchanger which has become blocked because the system was not cleaned when the same contractor fitted the boiler. So they charge again for what they failed to do within the installation cost.

The cold supply on DHW output pipes should be 15 mm as the mains pressure usually ensures enough flow IF the supply to the property can manage that. It should have been checked before the combi was specified! A combi will only supply one and a half taps at a time! I would pipe the combi direct from the supply point to minimise supply variations and restrict flow rates to CW outlets.

Pipes under the floor should be insulated but the heat loss from plastic is certainly less than copper.

Unless the boiler is beside the gas meter it will almost certainly need a 28 mm supply or larger. It should only lose 1 mB between the meter and boiler on full power. They are probably going to use an existing 22 mm pipe.

Tony

The first very important question is what is your current flow rate to the house as no matter what boiler you have and pipes size if the boiler does not have enough feed it will only splutter out what it gets.

As you you say if you are having a shower and someone flushes the loo they will be all feeding off the same feed.

Pete

Tony

i think you hit the nail on the head when you say inexperienced and cheap.

the questionis how do i get them to change the DHW outlet pipe from plastic to proper 15mm copper?

gas- yes they are using 22mm copper to supply the boiler, however the boiler is only 4-5m from the meter and the only other gas outlet is the kitchen, which is almost twice that distance away. would it still be a problem?

I am thinking of making a list of all the things they haven't done upto scratch, then mentioning these to the council man, when he comes to inspect...i'm not sure if he'll be able to do anything though.

Pete:

how do i check the current flow rate to the house, i dont have any special equiptment...however when they came to do a quote... the guy opened a tap and said the flow rate should be okay...not very scientific if you ask me!

thanks guys...this forum is great...i've never been on a forum where people reply so quickly.

Testing flowrate is pretty simple, get a graduated jug and see how long it takes to fill a litre then work out how many litres per min.

A visual test is not very accurate but does give a guide however if you are installing a high flow boiler this test should be carried out correctly.

Of course this only gives you the flow rate when one outlet is open maybe get someone to flush the toilet or open another outlet to see how much it drops to get an average.

Pete

Cowboy Rule No 1.

Never work for anyone with an ology.

Agile said:

That kind of firm specialises in using poorly paid and inexperienced staff and using the cheapest methods of working like using plastic pipe.

Click to expand...

Here we go again.

Even if a job using plastic pipe was always cheaper, which it isn't, cheaper doesn't equate to worse, in the same way that expensive doesn't equate to better.

Sider said:

Cowboy Rule No 1.

Never work for anyone with an ology.

Click to expand...

lol...haha...at least you put a smile on my face after four days of worrying that the hot water and heating in my house is doomed.

i think these cowboys need to learn a lesson

the thing i hate the most is that when i try and explain something to them they are in complete denial, and just say everything will be fine.

anyway...

i measured the flow rate using a jug:

cold water mains measure at my bath tap(which is pretty big): 22.5 litres/min

they also opened the cold water inlet into the boiler and hot water outlet from boiler yesterday, but the boiler hasn't been switched on yet. the water flow through the hot water taps is: 13.5litres/min - i am dissapointed by this because if when the boiler is switched off, and i can only get 13.5l/min, how am i ever going to get the 15.2l/min the boiler is suposed to provide?

last night i read through the vaillant installation manual and made a list of things they've fitted incorrectly...

1. the filling loop double check valve must only be attached/ connected when filling the central heating system, this has been left attached.

2. clearance of 5mm required either side of the boiler - on one side of the boiler the cold water supply pipe to the shower is touching the side of the boiler (can't see if they scratched the side of the boiler when fitting it in).

3. There should be a bottom clearance of 180mm below the condensate trap for removal and refitting, and this should be filled with water before operating the boiler - they have fitted (and soldered) the outlet pipe for the pressure relief valve in such a position that it is obstructing the condensate trap, and so the condensate trap cannot be removed (i'm not sure how they think they are going to fill this with water). the manual also says that if this is not filled with water, poisonous gases can escape into the room (i'm sure the media/press would like to know about a company that is being used by the council to fit hazardous boilers, and charge the council and me extortionate amounts (i pay a share and the council pays a share))!!!

4. I cant find a draining valve to drain the CH system - i doubt they have fitted one. This makes me wonder if they are even going to flush the system. the manual says the system must be flushed at least twice, once hot and once cold. there is something about the automatic air vent being loosened when filling the system, which i'm sure they didn't do.

they are due to commission the boiler today...so i'll be watching to make sure they do everything properly

i doubt they've ever fitted one of these vaillants before...but anyway...i'll keep you guys updated

cheers

physiologist said:

Hello everyone

i'm having my whole central heating system replaced from an old open vented system with microbore pipework to a new combi system with the boiler moved to the airing cupboard, by a 'professional' council approved company.

The bolier i have chosen is the ecotec 837 plus, primarily because of the high flow rate (we tend to use many taps at once in our house). we've got an a bathroom/ toilet with an electric shower plus another seperate toilet dowstairs.

I have a few questions if any of you kind guys could help me out:

1. the installers/ plumbers have used plastic hep20 pipes under the floorboards (the pipework looks very messy), is this recommended? and what are the chances it could leak? plus they haven't insulated the pipework under the floorboards downstairs - they say these pipes are already thermally insulated, do i still need foam insulation? (this is what hep20 say: http://www.hep2o.co.uk/v2Othermal.htm)

Click to expand...

Plastic has to be well clipped, more than copper, because of sagging when hot. This sagging puts strain on the joints. It NEEDS insulation on the pipes. Get them back to clip the pipes properly and insulate the pipes.

2. the other thing is that the DHW outlet from the boiler is a 15mm coper pipe, however they have connected this to the rest of the hot water system using a short piece of hep20 pipe, which has a much smaller inside diameter.

Click to expand...

It should be OK check the flowrate with a bucket and clock in litre/min

Also, do not accept plastic pipe if it is on show. New builds are plastic pipes, but copper onm show.

Like all physiologists i look at things from a scientific perspective, and according to poiselles law, flow is proportional to the cross sectional area of the pipe squared for a given pressure drop. hence the smaller pipe would theoretically limit the flow rate(and so the expesive bolier would become a waste of money). ive tried explaining this to the plumber but he doesn't seem to understand and says that this doesn't affect my boiler because my boiler has a high flow rate?!?!?!?

Click to expand...

Just check with a bucket.

they have done the same thing for the mains cold water inlet into the boiler, which itself is tapped off from the shower's water supply - i'm a little worried because if when i'm having and someone opens a hot water tap or flushes the loo, will this cause my shower to go cold or reduce flow on the boiler's DHW flow?

Click to expand...

The cold feed to the combi shuld be a dedicated supply taken back to the stop tap with no tee offs on this pipe. It should not be off the shower supply.

They should have installed in-line isolators on the other outlets to throttle down to "balance" the system to avoid the toilet robbing the combi of pressure and flow. E.g., a toilet doesn't need to fill very fast. Balancing a water system on a new combi installation is a standard thing to do.

If your shower mixer does not have an integral pressure equalisation vale (combi compatible shower mixers have these), they should have fitted a stand alone one on the shower hot and cold feed. This prevents scalding if soemone opens another cold tap.

Did they check the stop tap. Some of these restrict the flow. A full-bore stop-tap is madatory in some installations to improve pressureand flow.

We are paying this company a lot of money to do this job and we want to make sure its done properly? i really hate telling builders/ plumbers/ engineers how to do their job...but i'm the one who will have to live with this and so i might as well get it right first time.

could someone please advise?

cheers...sorry for the long post and waffle

Click to expand...

Pile up the info, like the Hep site and present it to them and tell them to get it fixed, otherwise you take legal action.

Also, if you got the company from the council list, approach them as well.

THe boiler has a 13l/min flow limiter on the hw to keep the temperature rise enough for a bath in the winter (42 degree rise).

Initial flushing is very important. The Brit Standard which most instructions refer to calls for full flow flush points on the system (ie TWO - one on flow one on return.) Fat chance with these guys.

It's important that a suitable chemical is put in the first water to get heated, it's circulated or flushed out(depending on layoout), then a corrsion inhibitor is added.
The gas supply is also very important. Get them to show you the inlet working pressure (which should be min 20mbar with boiler on max HW), which should be no more than 1mbar (theoretically) lower than the working pressure at the meter which they can also show you.
In practise if you have 19 at the boiler no problem - some meters only supply 19mbar in which case you'll have to accept 18 at the boiler.

Yes the downstair undefloor pipes must be insulated. The correct (regulation) stuff is about 3" diameter - costs a lot more than the pipe.

Water Systems :roll: said:

A full-bore stop-tap is madatory in some installations to improve pressureand flow.

Click to expand...

Not mandatory, it's prohibited. Contravenes water regulations to use one. Simply use a bigger stop cock if its resistance is significant.

the company are not from the council list, they are the only company the council is using to fit boilers on this scheme.

the company boss has agreed to insulate all the pipes after many phone call and intervention from the council (i think he's only doing this because when they did the survey they said they would insulate all pipes under the floor). However they are using thin <1cm thick foam insulation - i'm losing the will to live.

i think most of the outlets already have valves and so even if the dont throttle them back...i'll just do it myself.

i doubt they'll accept to redo the cold supply to the boiler so that its from the mains and not tapped off the boiler. i'm not sure what to do, maybe i'll tell the council.

this job has been so much hassle...next time i think i'll just fit everything myself and ignore the temptation of council grants.

i've lost the will to live

thanks again guys...btw if you have medical/ health questions do ask me and i'll try to answer them.

The issue becomes clouded if you have a grant aided installation as that could make the Council the "customer" of the installer.

If the installer is a reputable firm then they are likely to be members of the IPHE who will certainly investigate any complaints of bad workmanship. They may also be members of the HVCA but they are not very concerned about complaints from customers.

If you accept a grant aided scheme then it often limits you to having the cheapest job done which sometimes does not meet the generally accepted standards of workmanship expected in the industry for good quality installations.

Tony

ChrisR said:

Water Systems :roll: said:

A full-bore stop-tap is madatory in some installations to improve pressureand flow.

Click to expand...

Not mandatory, it's prohibited. Contravenes water regulations to use one. Simply use a bigger stop cock if its resistance is significant.

Click to expand...

Some water companies were charging £80 to change to one. Kent for e.g.

A bigger stop cock is better than the old tap, as they have the integral backflow prevention.

Water Systems said:

ChrisR said:

Water Systems :roll: said:

A full-bore stop-tap is madatory in some installations to improve pressureand flow.

Click to expand...

Not mandatory, it's prohibited. Contravenes water regulations to use one. Simply use a bigger stop cock if its resistance is significant.

Click to expand...

Some water companies were charging £80 to change to one. Kent for e.g.

A bigger stop cock is better than the old tap, as they have the integral backflow prevention.

Click to expand...

WOW

I nearly fell over, is this a climb down WS???????????? surely not as you know everything

ChrisR said:

Initial flushing is very important. The Brit Standard which most instructions refer to calls for full flow flush points on the system (ie TWO - one on flow one on return.) Fat chance with these guys.

Click to expand...

there is a drain valve for the CH but its under the floorboards, i don't know if there are 2 though.

do you still need to flush the system even if you have fitted new pipes and radiators on the CH? And how can i prove now that this wasn't done?

cheers