Setting up and balancing

[Jayelem]

I wanted to share some of my experiences with heating setup after I had a new boiler, controls and hot water cylinder fitted. The plumber who fitted it was, I think really experienced and capable, and worked hard (two men, two days) to finish off a very professional installation.
At switch-on, some radiators were a little cool, but after a quick balance, it was pronounced OK, and they left. Total cost for a Worcester 18Ri, cylinder, controller, thermostat, zone valve, tank stat., pump, Magnaclean and inhibitor was £3000. Expensive, but in line with other quotes I received. Overall, I was pleased.
Being an Engineer, though, I wasn't happy with the heat output; downstairs cooler than up, and one radiator particularly cold, whilst others boiled.
I wanted to balance the system properly, so I bought a non-contact IR thermometer (£12 from EBay) and this made the job very easy. I created a simple table of the temperature on both sides of each radiator, 10, 20, and 30 minutes after switch-on, and plotted a chart so I could see the results more easily. I also checked the top/bottom differential.
The first thing I did was look at the pump speed, as it seemed to be going very fast, and was a little noisy. Dropping it from 3 to 2 made little real effect, but 2 to 1 slowed the heat-up period, so I left it at 2.
Next, I balanced all the rads using my thermometer, and though this made a big improvement, the downstairs was still cooler. Conventional wisdom says downstairs cool is a pump fault, but with a new pump working OK, I knew this couldn't be right.
I then looked at the control system, and saw a manual bypass valve between flow and return. I have TRVs on all rads except the hall, where the thermostat is, so I figured I could close this down slightly to force more flow to the downstairs rads (I have a question on this, see below)
This made a massive difference, and the downstairs rads got much hotter, quicker.
Whilst I was there, I reasoned that the indirect coil on the cylinder is just another radiator, and also throttled this back via its manual valve in the return pipe.
The overall effect was astonishing, and the heating is now quicker, hotter and quieter. I did have some TRV whistling, but by opening the lockshield slightly, this went away (except on one occasion when a sharp tap on the valve body appeared to settle the jumper and stop the noise). Taking some flow from the cylinder and bypass has made all the difference.

The recommended pipe layout in the boiler installation notes shows two options; one with no bypass at all, and the other with an automatic bypass between flow and return. I believe that as I have one radiator without a TRV this will act as a bypass if all rads shut down and the cylinder valve is shut. Is this true? I didn't want to close down my manual bypass completely, so I just throttled it back a little, so the boiler can get its bypass via both the radiator and the bypass valve. Is this a good plan? I am not a plumber, but I think all the above is based on sound principles.
I guess I could work on the principle that if it's working it must be right, but I'm curious, so I'd appreciate any comments.
Doing this work wasn't difficult, but I guess you do need some understanding of heating systems, and a mechanical aptitude. I can understand and appreciate that a commercial plumber can't spend the hours I did, but conversely, had I been a little old lady, would I have had to put up with a very inefficient system? Where is the balance (no pun intended!) between profit and customer service?

 

[ecowarm]

A system should be balanced, bypass ajusted correctly. The system also needs to have the temp difference between flow and return correct as per the boiler instructions with the corect return temp so the boiler can condense.

 

[Best]

I think you have got it right. The cylinder is an important place to balance as it is just otherwise an open unrestricted large pipe which is short circuiting the pipework, therefore robbing the performance of the pump. The Bypass valve is obviously same, but on some open systems you have to be sure not to turn it too far as to cause system to pump into feed tank. I think, for a quick balance, the engineer should concentrate on the cyl & bypass more & rads are simple.

 

[kirkgas]

in this day an auto bypass is the way to go, once st it does its job by closing when the system is cold and opening pro rata as the circuit heats up and some TRV's close decreasing the system volume which can increase system noise on some installs, sounds as if the guys have done a decent job (although TBH balancing and making sure it works has always been a part of the install for me, not an afterthought when the punter complains,)

 

[Jayelem]

Thanks all for the replies. I'm still a little unsure of the answer to my major question, though; is a slightly-open bypass and one rad with no TRV an OK situation? I don't really want to go into a further install with an auto bypass. Everything seems to be working absolutely fine.

 

[kirkgas]

yes its "OK" but ok isnt 100% correct, but there are many 1000's of systems done like yours with no reported deaths so if all the rads are hot and the system isnt too noisy when there are only a couple of rads on then forget about it

 

[Jayelem]

Thanks. Great to have you guys around to share your experience.

 

[Best]

I'm still a little unsure of the answer to my major question, though; is a slightly-open bypass and one rad with no TRV an OK situation? .

Answer is probably! When you have only the one rad with no TRV on, the bypass should be open & if there are no problems, like pump noise or pumping up on open systems, then it should be ok. One of the important things about bypass valves is to have them opening only when they need to, & not too early, so to keep the pump doing it's job.

 

[twistednuts]

Depends on the controls you have and the position of the bypass. The bypass should be straight after the pump, before any motorized valves.

If its a "S" plan the bypass is for when both motorized valves are closed, otherwise the pump would be pumping against nothing on pump over run. The radiator wouldnt act as a bypass in this situation.

If its a "Y" plan then the radiator will work as a bypass only when the heating port is open.

The reason they have left a TRV off is probably because you dont have one on the radiator where the room stat is sited.

Hope this makes any sense.

 

[billybob150811]

i thought manual by-pass was now a no no and it had to be auto they can be difficult to set but you seem to have time to spend on this and engineers are both a pleasure and a pain as they must know whats going on fixed speed pumps dont lend themselves to fine adjustment you have what seems to be a good new system but unfortunatly very few people care about balancing the one rad you speak of should be 10% of the system volume in an ideal situation auto,s better as the trv,s close down the resistance to closing increases so without an efficient by-pass they may not shut off

 

[Jayelem]

I believe I should be OK then. The bypass is before the only motorised valve, and (I guess) provides a small but constant "leak" between flow and return, such that, under normal operation the bypass flow isn't significant, but will be there when the pump overrun needs it. As the bypass valve is a manual one, I also guess the setting has to be a compromise between not robbing the rads too much, and yet providing a bypass path. My logic (but I'm prepared to be wrong) is that with this path, plus the non-TRV rad is enough to meet the bypass needs.