tank fed system boiler, vent and fed positioning?

[AWheating]

I have bin to take a look at a heating system thats heating the office part of a commercial building. Last year it had a boiler change, im not sure what was there before. What has been put in is an Intergas combi boiler, tank fed on the heating side, the hot water side is not connected.

1, Any intergas installers know if intergas are happy with a tank fed set up?

2, if so what vent and feed set up do they recommend?

3, what do we think the best vent and feed setup would be in this installation (apart from sealing the system)

the current set up(old pipework) has the vent on the flow and the feed on the return, pointing towards the previous boiler being a different warren of rabbits. This has ment the system does not get very hot, and its always pumping over.

Apart from the obvious questions of the poor boiler job the system has alot of corrosion. Yes the current set up of pumping over will have made matters worse but it seems that the new boiler was fitted without the system ever being flushed as required. The benchmark reeks BS also.

The system has 35mm primary flow and returns with 20 large double radiators over a large working space. I am also questioning the choice of boiler regarding pump performance also. it also has a 22m magnetic filter on the return.

poor job all round it seems.





Adam.

intergas combi compact hre 36/40 btw

 

[Killy Bing]

open vent is fine, ccombine both before the return enters the boiler, thats what ive done on my open vent installs with the systems

what kw is the combi ?
how many floors ?
pump may not be man enough for the system which then leads you into putting in a low loss header

 

[AWheating]

open vent is fine, ccombine both before the return enters the boiler, thats what ive done on my open vent installs with the systems

what kw is the combi ?
how many floors ?
pump may not be man enough for the system which then leads you into putting in a low loss header

is that what intergas recommend?

2 floors, i agree the pump may not be man enough.

im not doing any work on it, just been asked by a friend to take a look and maybe quote a powerflush. But id rather point out the issues and let his boss discuss them with the company that did the boiler change.

system water is quite bad. def got alot of rust, def not had a good flush

 

[AWheating]

40kw boiler.

 

[Killy Bing]

i have no idea XD, thats what i did logicically off the top on my head but haven't had pumping over issues.

the combi will be set to 70% heating power out of the box, check that its been put upto 100% in the settings
and check they haven't turned the pump speed down to lessen the pumping over....

the boiler has 22mm water way, it iwll deal with alot of debris unlike most other boilers
not exactly good for but hey ho

 

[kris]

Hi Adam. I think the low loss headers a must for the size of system , you may see a big change once a power flush has been carried out n not need much Pipe alteration.

 

[Killy Bing]

i might add that wants an automatic bypass.

you can switch the pump out for a 7m head one by the way

 

[Hydroheat]

Hi AWheating, obviously, where about is the pump out of curiosity? I'm going to assume its in another location where the cylinder is and 3/2 ports are. The open vent and cold feed need to be just before the pump, else your systems pressure is going to be all over the place. Remember, as soon the cold feed enters the system it becomes and negative pressure, within 150mm of the cold feed there is a neutral zone, having your open vent connect just before the cold feed will be within the neutral zone. We say VIP - Vent Inlet Pump. thats the order you want to work with. I have a great image to show you but I'm not allowed to post URL's.

Another thing is the vent is connected from the side, the vent should act an air separator, so oxygen can rise out of it naturally, this is not going to happen so corrosion and sludge debris is always going to occur. Alter the vent to terminate from the top of the pipe. Also refer to the manufacturers I'm pretty sure there diagrams will show this set up.

The next thing is the pump, just have a look see what how much power there is behind it, take the screw out and stick a flat screw driver into it. You should be able to feel if its weak its quite obvious. Sticking a larger pump in may not be required.

I hope this helps you.

 

[AWheating]

its a combination boiler, the hot water side is not connected to anything, but its an intergas so not an issue.

ive spoke to the manufacturer and they recommend connection the feed and vent as KB suggested which makes sense and was what i was expecting but i needed it confirmed by them so i could do a written report on the problems. Also as KB noted it needs an auto bypass as the boiler does not have one built in.

one would hope the installer would have chosen this boiler knowing the pump was good enough for the index circuit of the system but who knows.

 

[Mike Jackson]

The 36/40 already has the 7m head pump installed. Check the speed hasn't been altered. Factory setting is iii but Intergas allow the installer to change the speed. The 36/40 comes set to 99% on heating but check this hasn't been altered.

 

[Hydroheat]

Sorry buddy, perhaps you can clear something up for me then, this combi boiler is tank fed?

 

[AWheating]

yes, tank fed on the heating side. some manufacturers allow it. intergas being one.

 

[Killy Bing]

The 36/40 already has the 7m head pump installed. Check the speed hasn't been altered. Factory setting is iii but Intergas allow the installer to change the speed. The 36/40 comes set to 99% on heating but check this hasn't been altered.

thanks mike
i coulden't get the M.I's up and was going off the top of my head

 

[Elgordo]

It should have been power flushed when new boiler was fitted , otherwise the guarantee is void . Get it done before you do anything else and you just might get away with existing pump

 

[Killy Bing]

It should have been power flushed when new boiler was fitted , otherwise the guarantee is void . Get it done before you do anything else and you just might get away with existing pump

Interesting

Does it have to be Power flushed or just a chemical flush?

 

[Mike Jackson]

Just needs to be cleansed. How you do it is up to you as long as it's clean enough. I find that I can get most systems clean enough with a magnacleanse. If they need more I mains flush after circulating a cleaner through the system hot and agitating the radiators until they are hot top to bottom.

 

[Killy Bing]

As per mike, powerflush isnt specifically required for the warranty.

Elgordo take a read of BS 7593

 

[Elgordo]

Thanks killy bing , me being over zealous .I always assume manufacturers will try anything to get out of honouring a guarantee and to that end I try to give them as little ammunition as possible in the event of a problem.